diff --git a/README.md b/README.md
index 66e1e6c80..37b970312 100644
--- a/README.md
+++ b/README.md
@@ -59,7 +59,7 @@ points = alt.Chart(source).mark_point().encode(
     x='Horsepower',
     y='Miles_per_Gallon',
     color=alt.condition(brush, 'Origin', alt.value('lightgray'))
-).add_parameter(
+).add_params(
     brush
 )
 
diff --git a/altair/examples/airport_connections.py b/altair/examples/airport_connections.py
index cc87adacf..ef1363abc 100644
--- a/altair/examples/airport_connections.py
+++ b/altair/examples/airport_connections.py
@@ -63,7 +63,7 @@
     from_=lookup_data
 ).transform_filter(
     (alt.datum.state != "PR") & (alt.datum.state != "VI")
-).add_parameter(
+).add_params(
     select_city
 )
 
diff --git a/altair/examples/dot_dash_plot.py b/altair/examples/dot_dash_plot.py
index c070d5c95..988b7a3bc 100644
--- a/altair/examples/dot_dash_plot.py
+++ b/altair/examples/dot_dash_plot.py
@@ -12,7 +12,7 @@
 
 # Configure the options common to all layers
 brush = alt.selection(type='interval')
-base = alt.Chart(source).add_parameter(brush)
+base = alt.Chart(source).add_params(brush)
 
 # Configure the points
 points = base.mark_point().encode(
diff --git a/altair/examples/histogram_responsive.py b/altair/examples/histogram_responsive.py
index 92c1ba3c8..79b7d48b9 100644
--- a/altair/examples/histogram_responsive.py
+++ b/altair/examples/histogram_responsive.py
@@ -31,5 +31,5 @@
   ),
   base.encode(
     alt.X('time:Q', bin=alt.Bin(maxbins=30)),
-  ).add_parameter(brush)
+  ).add_params(brush)
 )
diff --git a/altair/examples/interactive_brush.py b/altair/examples/interactive_brush.py
index 15509e2a3..13bffb4a0 100644
--- a/altair/examples/interactive_brush.py
+++ b/altair/examples/interactive_brush.py
@@ -16,4 +16,4 @@
     x='Horsepower:Q',
     y='Miles_per_Gallon:Q',
     color=alt.condition(brush, 'Cylinders:O', alt.value('grey')),
-).add_parameter(brush)
+).add_params(brush)
diff --git a/altair/examples/interactive_cross_highlight.py b/altair/examples/interactive_cross_highlight.py
index 51520f776..a167c0d20 100644
--- a/altair/examples/interactive_cross_highlight.py
+++ b/altair/examples/interactive_cross_highlight.py
@@ -38,7 +38,7 @@
 ).properties(
     width=550,
     height=200
-).add_parameter(pts)
+).add_params(pts)
 
 alt.vconcat(
     rect + circ,
diff --git a/altair/examples/interactive_layered_crossfilter.py b/altair/examples/interactive_layered_crossfilter.py
index 4c26080db..6a945b22d 100644
--- a/altair/examples/interactive_layered_crossfilter.py
+++ b/altair/examples/interactive_layered_crossfilter.py
@@ -29,7 +29,7 @@
 # gray background with selection
 background = base.encode(
     color=alt.value('#ddd')
-).add_parameter(brush)
+).add_params(brush)
 
 # blue highlights on the transformed data
 highlight = base.transform_filter(brush)
diff --git a/altair/examples/interactive_legend.py b/altair/examples/interactive_legend.py
index 491d78332..bd8b14b1a 100644
--- a/altair/examples/interactive_legend.py
+++ b/altair/examples/interactive_legend.py
@@ -18,6 +18,6 @@
     alt.Y('sum(count):Q', stack='center', axis=None),
     alt.Color('series:N', scale=alt.Scale(scheme='category20b')),
     opacity=alt.condition(selection, alt.value(1), alt.value(0.2))
-).add_parameter(
+).add_params(
     selection
 )
diff --git a/altair/examples/interval_selection.py b/altair/examples/interval_selection.py
index 50d7e28e1..509c200b8 100644
--- a/altair/examples/interval_selection.py
+++ b/altair/examples/interval_selection.py
@@ -27,6 +27,6 @@
 
 lower = base.properties(
     height=60
-).add_parameter(brush)
+).add_params(brush)
 
 upper & lower
diff --git a/altair/examples/multiline_highlight.py b/altair/examples/multiline_highlight.py
index cc2a32daa..a6a172c4f 100644
--- a/altair/examples/multiline_highlight.py
+++ b/altair/examples/multiline_highlight.py
@@ -23,7 +23,7 @@
 
 points = base.mark_circle().encode(
     opacity=alt.value(0)
-).add_parameter(
+).add_params(
     highlight
 ).properties(
     width=600
diff --git a/altair/examples/multiline_tooltip.py b/altair/examples/multiline_tooltip.py
index 4c9ae1a6d..0a242e74e 100644
--- a/altair/examples/multiline_tooltip.py
+++ b/altair/examples/multiline_tooltip.py
@@ -38,7 +38,7 @@
 selectors = alt.Chart(source).mark_point().encode(
     x='x:Q',
     opacity=alt.value(0),
-).add_parameter(
+).add_params(
     nearest
 )
 
diff --git a/altair/examples/multiple_interactions.py b/altair/examples/multiple_interactions.py
index 3cc5ecb30..e11905018 100644
--- a/altair/examples/multiple_interactions.py
+++ b/altair/examples/multiple_interactions.py
@@ -42,7 +42,7 @@
 slider_selection = alt.selection_point(bind=year_slider, fields=['Release_Year'], name="Release Year_")
 
 
-filter_year = base.add_parameter(
+filter_year = base.add_params(
     slider_selection
 ).transform_filter(
     slider_selection
@@ -52,7 +52,7 @@
 genre_dropdown = alt.binding_select(options=genres)
 genre_select = alt.selection_point(fields=['Major_Genre'], bind=genre_dropdown, name="Genre")
 
-filter_genres = base.add_parameter(
+filter_genres = base.add_params(
     genre_select
 ).transform_filter(
     genre_select
@@ -66,7 +66,7 @@
                       alt.Color('MPAA_Rating:N', legend=None),
                       alt.value('lightgray'))
 
-highlight_ratings = base.add_parameter(
+highlight_ratings = base.add_params(
     rating_select
 ).encode(
     color=rating_color_condition
@@ -81,7 +81,7 @@
                                         alt.Size('Hundred_Million_Production:Q')
                                        )
 
-budget_sizing = base.add_parameter(
+budget_sizing = base.add_params(
     checkbox_selection
 ).encode(
     size=size_checkbox_condition
diff --git a/altair/examples/scatter_linked_brush.py b/altair/examples/scatter_linked_brush.py
index 23a92dddf..399cdb667 100644
--- a/altair/examples/scatter_linked_brush.py
+++ b/altair/examples/scatter_linked_brush.py
@@ -15,7 +15,7 @@
 base = alt.Chart(source).mark_point().encode(
     y='Miles_per_Gallon',
     color=alt.condition(brush, 'Origin', alt.ColorValue('gray')),
-).add_parameter(
+).add_params(
     brush
 ).properties(
     width=250,
diff --git a/altair/examples/scatter_linked_table.py b/altair/examples/scatter_linked_table.py
index 0f414a682..582cd53bc 100644
--- a/altair/examples/scatter_linked_table.py
+++ b/altair/examples/scatter_linked_table.py
@@ -19,7 +19,7 @@
     x='Horsepower:Q',
     y='Miles_per_Gallon:Q',
     color=alt.condition(brush, 'Cylinders:O', alt.value('grey'))
-).add_parameter(brush)
+).add_params(brush)
 
 # Base chart for data tables
 ranked_text = alt.Chart(source).mark_text().encode(
diff --git a/altair/examples/scatter_with_histogram.py b/altair/examples/scatter_with_histogram.py
index f4ea4902a..f230c5f50 100644
--- a/altair/examples/scatter_with_histogram.py
+++ b/altair/examples/scatter_with_histogram.py
@@ -46,7 +46,7 @@
 ).properties(
     width=300,
     height=300
-).add_parameter(pts)
+).add_params(pts)
 
 # build the chart:
 alt.hconcat(
diff --git a/altair/examples/scatter_with_layered_histogram.py b/altair/examples/scatter_with_layered_histogram.py
index 0c6bede07..2268b055c 100644
--- a/altair/examples/scatter_with_layered_histogram.py
+++ b/altair/examples/scatter_with_layered_histogram.py
@@ -34,7 +34,7 @@
 base = alt.Chart(source).properties(
     width=250,
     height=250
-).add_parameter(selector)
+).add_params(selector)
 
 points = base.mark_point(filled=True, size=200).encode(
     x=alt.X('mean(height):Q', scale=alt.Scale(domain=[0,84])),
diff --git a/altair/examples/scatter_with_minimap.py b/altair/examples/scatter_with_minimap.py
index 254736bea..a18a599cd 100644
--- a/altair/examples/scatter_with_minimap.py
+++ b/altair/examples/scatter_with_minimap.py
@@ -17,7 +17,7 @@
 minimap = (
     alt.Chart(source)
     .mark_point()
-    .add_parameter(zoom)
+    .add_params(zoom)
     .encode(
         x="date:T",
         y="temp_max:Q",
diff --git a/altair/examples/seattle_weather_interactive.py b/altair/examples/seattle_weather_interactive.py
index 3bbd413d1..798cc4780 100644
--- a/altair/examples/seattle_weather_interactive.py
+++ b/altair/examples/seattle_weather_interactive.py
@@ -33,7 +33,7 @@
 ).properties(
     width=550,
     height=300
-).add_parameter(
+).add_params(
     brush
 ).transform_filter(
     click
@@ -48,7 +48,7 @@
     brush
 ).properties(
     width=550,
-).add_parameter(
+).add_params(
     click
 )
 
diff --git a/altair/examples/select_detail.py b/altair/examples/select_detail.py
index 781f986ca..a6b558df7 100644
--- a/altair/examples/select_detail.py
+++ b/altair/examples/select_detail.py
@@ -46,7 +46,7 @@
 base = alt.Chart(data).properties(
     width=250,
     height=250
-).add_parameter(selector)
+).add_params(selector)
 
 points = base.mark_point(filled=True, size=200).encode(
     x='mean(x)',
diff --git a/altair/examples/select_mark_area.py b/altair/examples/select_mark_area.py
index 93bf3ffb4..9750f7a74 100644
--- a/altair/examples/select_mark_area.py
+++ b/altair/examples/select_mark_area.py
@@ -24,7 +24,7 @@
 )
 
 brush = alt.selection_interval(encodings=['x'])
-background = base.add_parameter(brush)
+background = base.add_params(brush)
 selected = base.transform_filter(brush).mark_area(color='goldenrod')
 
 background + selected
diff --git a/altair/examples/selection_histogram.py b/altair/examples/selection_histogram.py
index e9c4e0cb2..aabf62a5d 100644
--- a/altair/examples/selection_histogram.py
+++ b/altair/examples/selection_histogram.py
@@ -17,7 +17,7 @@
     x='Horsepower:Q',
     y='Miles_per_Gallon:Q',
     color=alt.condition(brush, 'Origin:N', alt.value('lightgray'))
-).add_parameter(
+).add_params(
     brush
 )
 
diff --git a/altair/examples/selection_layer_bar_month.py b/altair/examples/selection_layer_bar_month.py
index 9eff6395b..33c081f2d 100644
--- a/altair/examples/selection_layer_bar_month.py
+++ b/altair/examples/selection_layer_bar_month.py
@@ -16,7 +16,7 @@
     x='month(date):O',
     y='mean(precipitation):Q',
     opacity=alt.condition(brush, alt.OpacityValue(1), alt.OpacityValue(0.7)),
-).add_parameter(
+).add_params(
     brush
 )
 
diff --git a/altair/examples/slider_cutoff.py b/altair/examples/slider_cutoff.py
index b59850c39..19db77493 100644
--- a/altair/examples/slider_cutoff.py
+++ b/altair/examples/slider_cutoff.py
@@ -16,7 +16,7 @@
 })
 
 slider = alt.binding_range(min=0, max=100, step=1)
-cutoff = alt.parameter(bind=slider, value=50)
+cutoff = alt.param(bind=slider, value=50)
 
 alt.Chart(df).mark_point().encode(
     x='xval',
@@ -25,6 +25,6 @@
         alt.datum.xval < cutoff,
         alt.value('red'), alt.value('blue')
     )
-).add_parameter(
+).add_params(
     cutoff
 )
\ No newline at end of file
diff --git a/altair/examples/us_population_over_time.py b/altair/examples/us_population_over_time.py
index b59d5c8f5..52e5290a0 100644
--- a/altair/examples/us_population_over_time.py
+++ b/altair/examples/us_population_over_time.py
@@ -30,7 +30,7 @@
 ).properties(
     width=20,
     title="U.S. Population by Age and Sex"
-).add_parameter(
+).add_params(
     select_year
 ).transform_calculate(
     "sex", alt.expr.if_(alt.datum.sex == 1, "Male", "Female")
diff --git a/altair/examples/us_population_pyramid_over_time.py b/altair/examples/us_population_pyramid_over_time.py
index 2304f58e2..4857adf6a 100644
--- a/altair/examples/us_population_pyramid_over_time.py
+++ b/altair/examples/us_population_pyramid_over_time.py
@@ -15,7 +15,7 @@
 select_year = alt.selection_point(name='year', fields=['year'],
                                    bind=slider, value={'year': 2000})
 
-base = alt.Chart(source).add_parameter(
+base = alt.Chart(source).add_params(
     select_year
 ).transform_filter(
     select_year
diff --git a/altair/examples/us_state_capitals.py b/altair/examples/us_state_capitals.py
index fcc42efdd..47c9e9d13 100644
--- a/altair/examples/us_state_capitals.py
+++ b/altair/examples/us_state_capitals.py
@@ -38,6 +38,6 @@
 points = base.mark_point().encode(
     color=alt.value('black'),
     size=alt.condition(~hover, alt.value(30), alt.value(100))
-).add_parameter(hover)
+).add_params(hover)
 
 background + points + text
diff --git a/altair/vegalite/v5/api.py b/altair/vegalite/v5/api.py
index c84a33fb6..8c468a207 100644
--- a/altair/vegalite/v5/api.py
+++ b/altair/vegalite/v5/api.py
@@ -214,7 +214,7 @@ def _to_expr(self):
             return self.param.expr
 
     def _from_expr(self, expr):
-        return parameter(expr=expr)
+        return param(expr=expr)
 
     def __getattr__(self, field_name):
         if field_name.startswith("__") and field_name.endswith("__"):
@@ -278,7 +278,7 @@ def value(value, **kwargs):
     return dict(value=value, **kwargs)
 
 
-def parameter(name=None, select=None, **kwds):
+def param(name=None, select=None, **kwds):
     """Create a named parameter.
 
     Parameters
@@ -379,7 +379,7 @@ def selection(type=Undefined, **kwds):
     else:
         raise ValueError("""'type' must be 'point' or 'interval'""")
 
-    return parameter(select=select, **param_kwds)
+    return param(select=select, **param_kwds)
 
 
 @utils.use_signature(core.IntervalSelectionConfig)
@@ -2184,7 +2184,7 @@ def to_dict(self, *args, **kwargs):
             return super(Chart, copy).to_dict(*args, **kwargs)
         return super().to_dict(*args, **kwargs)
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params:
             return self
@@ -2197,10 +2197,10 @@ def add_parameter(self, *params):
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *params):
-        return self.add_parameter(*params)
+        return self.add_params(*params)
 
     def interactive(self, name=None, bind_x=True, bind_y=True):
         """Make chart axes scales interactive
@@ -2226,9 +2226,7 @@ def interactive(self, name=None, bind_x=True, bind_y=True):
             encodings.append("x")
         if bind_y:
             encodings.append("y")
-        return self.add_parameter(
-            selection_interval(bind="scales", encodings=encodings)
-        )
+        return self.add_params(selection_interval(bind="scales", encodings=encodings))
 
 
 def _check_if_valid_subspec(spec, classname):
@@ -2364,19 +2362,19 @@ def interactive(self, name=None, bind_x=True, bind_y=True):
         copy.spec = copy.spec.interactive(name=name, bind_x=bind_x, bind_y=bind_y)
         return copy
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params or self.spec is Undefined:
             return self
         copy = self.copy()
-        copy.spec = copy.spec.add_parameter(*params)
+        copy.spec = copy.spec.add_params(*params)
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *selections):
-        return self.add_parameter(*selections)
+        return self.add_params(*selections)
 
 
 def repeat(repeater="repeat"):
@@ -2423,19 +2421,19 @@ def __or__(self, other):
         copy |= other
         return copy
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params or not self.concat:
             return self
         copy = self.copy()
-        copy.concat = [chart.add_parameter(*params) for chart in copy.concat]
+        copy.concat = [chart.add_params(*params) for chart in copy.concat]
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *selections):
-        return self.add_parameter(*selections)
+        return self.add_params(*selections)
 
 
 def concat(*charts, **kwargs):
@@ -2465,19 +2463,19 @@ def __or__(self, other):
         copy |= other
         return copy
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params or not self.hconcat:
             return self
         copy = self.copy()
-        copy.hconcat = [chart.add_parameter(*params) for chart in copy.hconcat]
+        copy.hconcat = [chart.add_params(*params) for chart in copy.hconcat]
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *selections):
-        return self.add_parameter(*selections)
+        return self.add_params(*selections)
 
 
 def hconcat(*charts, **kwargs):
@@ -2507,19 +2505,19 @@ def __and__(self, other):
         copy &= other
         return copy
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params or not self.vconcat:
             return self
         copy = self.copy()
-        copy.vconcat = [chart.add_parameter(*params) for chart in copy.vconcat]
+        copy.vconcat = [chart.add_params(*params) for chart in copy.vconcat]
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *selections):
-        return self.add_parameter(*selections)
+        return self.add_params(*selections)
 
 
 def vconcat(*charts, **kwargs):
@@ -2594,19 +2592,19 @@ def interactive(self, name=None, bind_x=True, bind_y=True):
         )
         return copy
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params or not self.layer:
             return self
         copy = self.copy()
-        copy.layer[0] = copy.layer[0].add_parameter(*params)
+        copy.layer[0] = copy.layer[0].add_params(*params)
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *selections):
-        return self.add_parameter(*selections)
+        return self.add_params(*selections)
 
 
 def layer(*charts, **kwargs):
@@ -2645,19 +2643,19 @@ def interactive(self, name=None, bind_x=True, bind_y=True):
         copy.spec = copy.spec.interactive(name=name, bind_x=bind_x, bind_y=bind_y)
         return copy
 
-    def add_parameter(self, *params):
+    def add_params(self, *params):
         """Add one or more parameters to the chart."""
         if not params or self.spec is Undefined:
             return self
         copy = self.copy()
-        copy.spec = copy.spec.add_parameter(*params)
+        copy.spec = copy.spec.add_params(*params)
         return copy
 
     @utils.deprecation.deprecated(
-        message="'add_selection' is deprecated. Use 'add_parameter' instead."
+        message="'add_selection' is deprecated. Use 'add_params' instead."
     )
     def add_selection(self, *selections):
-        return self.add_parameter(*selections)
+        return self.add_params(*selections)
 
 
 def topo_feature(url, feature, **kwargs):
diff --git a/altair/vegalite/v5/tests/test_api.py b/altair/vegalite/v5/tests/test_api.py
index 535538f42..9bd52ef2e 100644
--- a/altair/vegalite/v5/tests/test_api.py
+++ b/altair/vegalite/v5/tests/test_api.py
@@ -394,8 +394,8 @@ def test_selection():
     assert multi.name == "selec_3"
 
     # test adding to chart
-    chart = alt.Chart().add_parameter(single)
-    chart = chart.add_parameter(multi, interval)
+    chart = alt.Chart().add_params(single)
+    chart = chart.add_params(multi, interval)
     assert set(x.name for x in chart.params) == {"selec_1", "selec_2", "selec_3"}
 
     # test logical operations
@@ -596,8 +596,8 @@ def test_add_selection():
     chart = (
         alt.Chart()
         .mark_point()
-        .add_parameter(selections[0])
-        .add_parameter(selections[1], selections[2])
+        .add_params(selections[0])
+        .add_params(selections[1], selections[2])
     )
     expected = [s.param for s in selections]
     assert chart.params == expected
@@ -606,24 +606,24 @@ def test_add_selection():
 def test_repeat_add_selections():
     base = alt.Chart("data.csv").mark_point()
     selection = alt.selection_point()
-    chart1 = base.add_parameter(selection).repeat(list("ABC"))
-    chart2 = base.repeat(list("ABC")).add_parameter(selection)
+    chart1 = base.add_params(selection).repeat(list("ABC"))
+    chart2 = base.repeat(list("ABC")).add_params(selection)
     assert chart1.to_dict() == chart2.to_dict()
 
 
 def test_facet_add_selections():
     base = alt.Chart("data.csv").mark_point()
     selection = alt.selection_point()
-    chart1 = base.add_parameter(selection).facet("val:Q")
-    chart2 = base.facet("val:Q").add_parameter(selection)
+    chart1 = base.add_params(selection).facet("val:Q")
+    chart2 = base.facet("val:Q").add_params(selection)
     assert chart1.to_dict() == chart2.to_dict()
 
 
 def test_layer_add_selection():
     base = alt.Chart("data.csv").mark_point()
     selection = alt.selection_point()
-    chart1 = alt.layer(base.add_parameter(selection), base)
-    chart2 = alt.layer(base, base).add_parameter(selection)
+    chart1 = alt.layer(base.add_params(selection), base)
+    chart2 = alt.layer(base, base).add_params(selection)
     assert chart1.to_dict() == chart2.to_dict()
 
 
@@ -631,8 +631,8 @@ def test_layer_add_selection():
 def test_compound_add_selections(charttype):
     base = alt.Chart("data.csv").mark_point()
     selection = alt.selection_point()
-    chart1 = charttype(base.add_parameter(selection), base.add_parameter(selection))
-    chart2 = charttype(base, base).add_parameter(selection)
+    chart1 = charttype(base.add_params(selection), base.add_params(selection))
+    chart2 = charttype(base, base).add_params(selection)
     assert chart1.to_dict() == chart2.to_dict()
 
 
diff --git a/doc/case_studies/exploring-weather.rst b/doc/case_studies/exploring-weather.rst
index 6146de4fb..9eac497ae 100644
--- a/doc/case_studies/exploring-weather.rst
+++ b/doc/case_studies/exploring-weather.rst
@@ -237,7 +237,7 @@ of the selection (for more information on selections, see
     ).properties(
         width=600,
         height=400
-    ).add_parameter(
+    ).add_params(
         brush
     )
 
diff --git a/doc/releases/changes.rst b/doc/releases/changes.rst
index 9b5ff7544..8b20967bd 100644
--- a/doc/releases/changes.rst
+++ b/doc/releases/changes.rst
@@ -15,7 +15,7 @@ Enhancements
 Grammar Changes
 ~~~~~~~~~~~~~~~
 - ``selection_single`` and ``selection_multi`` are now deprecated; use ``selection_point`` instead.  Similarly, ``type=point`` should be used instead of ``type=single`` and ``type=multi``.
-- ``add_selection`` is deprecated; use ``add_parameter`` instead.
+- ``add_selection`` is deprecated; use ``add_params`` instead.
 - The ``selection`` keyword argument must in many cases be replaced by ``param`` (e.g., when specifying a filter transform).
 - The ``empty`` keyword argument for a selection parameter should be specified as ``True`` or ``False`` instead of ``all`` or ``none``, respectively.
 - The ``init`` keyword argument for a parameter is deprecated; use ``value`` instead.
diff --git a/doc/user_guide/compound_charts.rst b/doc/user_guide/compound_charts.rst
index d85f322ba..6234faee9 100644
--- a/doc/user_guide/compound_charts.rst
+++ b/doc/user_guide/compound_charts.rst
@@ -195,7 +195,7 @@ with a ``brush`` selection to add interaction:
 
     lower = base.properties(
         height=60
-    ).add_parameter(brush)
+    ).add_params(brush)
 
     alt.vconcat(upper, lower)
 
@@ -373,7 +373,7 @@ layered chart with a hover selection:
         height=180,
     )
 
-    points = base.mark_point().add_parameter(
+    points = base.mark_point().add_params(
         hover
     )
 
diff --git a/doc/user_guide/interactions.rst b/doc/user_guide/interactions.rst
index 3cfbee39c..80b75b760 100644
--- a/doc/user_guide/interactions.rst
+++ b/doc/user_guide/interactions.rst
@@ -60,9 +60,9 @@ We can create a variable parameter using :func:`parameter`, and assign that para
 .. altair-plot::
     :output: none
 
-    op_var = alt.parameter(value=0.1)
+    op_var = alt.param(value=0.1)
 
-In order to use this variable in the chart specification, we explicitly add it to the chart using the :meth:`Chart.add_parameter` method, and we can then reference the variable within the chart specification.  Here we set the opacity using our ``op_var`` parameter.
+In order to use this variable in the chart specification, we explicitly add it to the chart using the :meth:`Chart.add_params` method, and we can then reference the variable within the chart specification.  Here we set the opacity using our ``op_var`` parameter.
 
 .. altair-plot::
 
@@ -71,17 +71,17 @@ In order to use this variable in the chart specification, we explicitly add it t
 
     cars = data.cars.url
 
-    op_var = alt.parameter(value=0.1)
+    op_var = alt.param(value=0.1)
 
     alt.Chart(cars).mark_circle(opacity=op_var).encode(
         x='Miles_per_Gallon:Q',
         y='Horsepower:Q',
         color='Origin:N'
-    ).add_parameter(
+    ).add_params(
         op_var
     )
 
-It's reasonable to ask whether all this effort is necessary.  Here is a more natural way to accomplish the same thing.  We avoid the use of both :func:`alt.parameter` and ``add_parameter``.
+It's reasonable to ask whether all this effort is necessary.  Here is a more natural way to accomplish the same thing.  We avoid the use of both :func:`alt.param` and ``add_params``.
 
 .. altair-plot::
 
@@ -98,7 +98,7 @@ It's reasonable to ask whether all this effort is necessary.  Here is a more nat
         color='Origin:N'
     )
 
-The benefit of using :func:`alt.parameter` doesn't become apparent until we incorporate an additional component, such as in the following, where we use the ``bind`` property of the parameter, so that the parameter becomes bound to an input element.  In this example, that input element is a slider widget.
+The benefit of using :func:`alt.param` doesn't become apparent until we incorporate an additional component, such as in the following, where we use the ``bind`` property of the parameter, so that the parameter becomes bound to an input element.  In this example, that input element is a slider widget.
 
 .. altair-plot::
 
@@ -108,13 +108,13 @@ The benefit of using :func:`alt.parameter` doesn't become apparent until we inco
     cars = data.cars.url
 
     slider = alt.binding_range(min=0, max=1, step=0.05, name='opacity:')
-    op_var = alt.parameter(value=0.1, bind=slider)
+    op_var = alt.param(value=0.1, bind=slider)
 
     alt.Chart(cars).mark_circle(opacity=op_var).encode(
         x='Miles_per_Gallon:Q',
         y='Horsepower:Q',
         color='Origin:N'
-    ).add_parameter(
+    ).add_params(
         op_var
     )
 
@@ -123,7 +123,7 @@ Now we can dynamically change the opacity of the points in our chart using the s
 The above example includes some aspects which occur frequently when creating interactive charts in Altair:
 
 1. Creating a variable parameter using :func:`parameter`.
-2. Attaching the parameter to a chart using the :meth:`Chart.add_parameter` method.
+2. Attaching the parameter to a chart using the :meth:`Chart.add_params` method.
 3. Binding the parameter to an input widget (such as the slider above) using the parameter's ``bind`` property.
 
 
@@ -137,7 +137,7 @@ There are two types of selections:
 :func:`selection_interval` and :func:`selection_point`.
 
 Here we will create a simple chart and then add an selection interval to it.
-We could create a selection interval via ``alt.parameter(select="interval")``,
+We could create a selection interval via ``alt.param(select="interval")``,
 but it is more convenient to use the shorter ``alt.selection_interval``
 (and this also matches the syntax that was used in Altair 4).
 
@@ -173,7 +173,7 @@ property:
         x='Miles_per_Gallon:Q',
         y='Horsepower:Q',
         color='Origin:N'
-    ).add_parameter(
+    ).add_params(
         brush
     )
 
@@ -182,7 +182,7 @@ a selection region, and to move this region once the region is created.
 
 So far this example is very similar to what we did in the :ref:`variable example <basic variable>`:
 we created a selection parameter using ``brush = alt.selection_interval()``,
-and we attached that parameter to the chart using ``add_parameter``.
+and we attached that parameter to the chart using ``add_params``.
 
 Conditions: Making the Chart Respond
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -200,7 +200,7 @@ for points outside the selection:
         x='Miles_per_Gallon:Q',
         y='Horsepower:Q',
         color=alt.condition(brush, 'Origin:N', alt.value('lightgray'))
-    ).add_parameter(
+    ).add_params(
         brush
     )
 
@@ -231,7 +231,7 @@ tied to ``"Miles_per_Gallon"``
     ).properties(
         width=250,
         height=250
-    ).add_parameter(
+    ).add_params(
         brush
     )
 
@@ -257,7 +257,7 @@ We can modify the brush definition, and leave the rest of the code unchanged:
     ).properties(
         width=250,
         height=250
-    ).add_parameter(
+    ).add_params(
         brush
     )
 
@@ -287,7 +287,7 @@ selection:
         ).properties(
             width=300,
             height=180
-        ).add_parameter(
+        ).add_params(
             selector
         )
 
@@ -326,7 +326,7 @@ chart scales; this is how Altair plots can be made interactive:
         x='Horsepower:Q',
         y='Miles_per_Gallon:Q',
         color='Origin:N'
-    ).add_parameter(
+    ).add_params(
         scales
     )
 
@@ -401,7 +401,7 @@ selection.
         x='Cylinders:O',
         y='Origin:O',
         color=alt.condition(alex | morgan, 'count()', alt.ColorValue("grey"))
-    ).add_parameter(
+    ).add_params(
         alex, morgan
     ).properties(
         width=300,
@@ -446,7 +446,7 @@ with a matching ``Origin``.
     legend = alt.Chart(cars).mark_point().encode(
         y=alt.Y('Origin:N', axis=alt.Axis(orient='right')),
         color=color
-    ).add_parameter(
+    ).add_params(
         selection
     )
 
@@ -480,7 +480,7 @@ cylinders:
         y=alt.Y('Origin:N', axis=alt.Axis(orient='right')),
         x='Cylinders:O',
         color=color
-    ).add_parameter(
+    ).add_params(
         selection
     )
 
@@ -516,7 +516,7 @@ depending on the size and position of the selection in the scatter plot.
         x='Horsepower:Q',
         y='Miles_per_Gallon:Q',
         color='Origin:N'
-    ).add_parameter(
+    ).add_params(
         brush
     )
 
@@ -557,7 +557,7 @@ For instance, using our example from above a dropdown can be used to highlight c
         y='Miles_per_Gallon:Q',
         color=color,
         tooltip='Name:N'
-    ).add_parameter(
+    ).add_params(
         selection
     )
 
@@ -591,7 +591,7 @@ Bindings and input elements can also be used to filter data on the client side.
         y='Miles_per_Gallon:Q',
         color='Origin:N',
         tooltip='Name:N'
-    ).add_parameter(
+    ).add_params(
         selection
     ).transform_filter(
         selection
@@ -611,7 +611,7 @@ With interval selections, the ``bind`` property can be set to the value of ``"sc
         y='Miles_per_Gallon:Q',
         color='Origin:N',
         tooltip='Name:N'
-    ).add_parameter(
+    ).add_params(
         selection
     )
 
@@ -651,7 +651,7 @@ points based on whether they are smaller or larger than the value:
            # 'datum.xval < SelectorName.cutoff',  # An equivalent alternative
            alt.value('red'), alt.value('blue')
        )
-   ).add_parameter(
+   ).add_params(
        selector
    )
 
@@ -673,7 +673,7 @@ since they can also be accessed in expression strings:
 .. altair-plot::
 
     slider = alt.binding_range(min=0, max=100, step=1, name='Cutoff ')
-    selector = alt.parameter(name='SelectorName', value=50, bind=slider)
+    selector = alt.param(name='SelectorName', value=50, bind=slider)
 
     alt.Chart(df).mark_point().encode(
        x='xval',
@@ -683,7 +683,7 @@ since they can also be accessed in expression strings:
            # 'datum.xval < SelectorName',  # An equivalent alternative
            alt.value('red'), alt.value('blue')
        )
-    ).add_parameter(
+    ).add_params(
        selector
     )
 
@@ -741,7 +741,7 @@ Taking advantage of the parameter interface introduced in Altair 5, we can expre
         options=['Miles_per_Gallon', 'Displacement', 'Weight_in_lbs', 'Acceleration'],
         name='X-axis column '
     )
-    param = alt.parameter(
+    param = alt.param(
         name='selected_column',
         value='Miles_per_Gallon',
         bind=dropdown
@@ -753,6 +753,6 @@ Taking advantage of the parameter interface introduced in Altair 5, we can expre
         color='Origin:N'
     ).transform_calculate(
         x='datum[selected_column]'
-    ).add_parameter(
+    ).add_params(
         param
     )
diff --git a/doc/user_guide/transform/filter.rst b/doc/user_guide/transform/filter.rst
index 733d9a1dd..869a92d33 100644
--- a/doc/user_guide/transform/filter.rst
+++ b/doc/user_guide/transform/filter.rst
@@ -151,7 +151,7 @@ to select the data to be shown in the top chart:
         color=alt.condition(selection, alt.value('steelblue'), alt.value('lightgray'))
     ).properties(
         width=600, height=100
-    ).add_parameter(
+    ).add_params(
         selection
     )
 
diff --git a/doc/user_guide/transform/pivot.rst b/doc/user_guide/transform/pivot.rst
index 4b5ce297f..7ac269e2c 100644
--- a/doc/user_guide/transform/pivot.rst
+++ b/doc/user_guide/transform/pivot.rst
@@ -61,7 +61,7 @@ values on multiple lines:
    ).mark_rule().encode(
        opacity=alt.condition(selection, alt.value(0.3), alt.value(0)),
        tooltip=[alt.Tooltip(c, type='quantitative') for c in columns]
-   ).add_parameter(selection)
+   ).add_params(selection)
    
    lines + points + rule