diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0bc0648f16a..93072979516 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,9 @@ release.
 
 ### Metrics
 
+- Add the OptIn advisory parameter.
+  ([#4809](https://github.com/open-telemetry/opentelemetry-specification/pull/4809))
+
 ### Logs
 
 ### Baggage
diff --git a/spec-compliance-matrix.md b/spec-compliance-matrix.md
index 116a3b786cc..23cc47f9d94 100644
--- a/spec-compliance-matrix.md
+++ b/spec-compliance-matrix.md
@@ -130,6 +130,7 @@ formats is required. Implementing more than one format is optional.
 | Instrument descriptions conform to the specified syntax. |  | - | + |  | - | + | + |  |  | - | + |  |
 | Instrument supports the advisory ExplicitBucketBoundaries parameter. |  | + | + |  |  |  | + |  |  |  |  |  |
 | Instrument supports the advisory Attributes parameter. |  | - | + |  |  |  | + |  |  |  |  |  |
+| Instrument supports the advisory OptIn parameter. |  | - | - | - | - | - | - | - | - | - | - | - |
 | All methods of `MeterProvider` are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
 | All methods of `Meter` are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
 | All methods of any instrument are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
diff --git a/spec-compliance-matrix/cpp.yaml b/spec-compliance-matrix/cpp.yaml
index 65ae3abfe76..cba61a615ac 100644
--- a/spec-compliance-matrix/cpp.yaml
+++ b/spec-compliance-matrix/cpp.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/dotnet.yaml b/spec-compliance-matrix/dotnet.yaml
index f5d51a066d3..da8a933b50b 100644
--- a/spec-compliance-matrix/dotnet.yaml
+++ b/spec-compliance-matrix/dotnet.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/erlang.yaml b/spec-compliance-matrix/erlang.yaml
index 7d5d680d6a5..e42d3231bef 100644
--- a/spec-compliance-matrix/erlang.yaml
+++ b/spec-compliance-matrix/erlang.yaml
@@ -223,6 +223,8 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '+'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/go.yaml b/spec-compliance-matrix/go.yaml
index 7b3fb26a4b6..c79d6474093 100644
--- a/spec-compliance-matrix/go.yaml
+++ b/spec-compliance-matrix/go.yaml
@@ -223,6 +223,8 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '-'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/java.yaml b/spec-compliance-matrix/java.yaml
index e3fe29f9ad3..33fec46a511 100644
--- a/spec-compliance-matrix/java.yaml
+++ b/spec-compliance-matrix/java.yaml
@@ -223,6 +223,8 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '+'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/js.yaml b/spec-compliance-matrix/js.yaml
index a7154980e30..3739111b8b0 100644
--- a/spec-compliance-matrix/js.yaml
+++ b/spec-compliance-matrix/js.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/php.yaml b/spec-compliance-matrix/php.yaml
index 1d506cafd6f..8e7587015ce 100644
--- a/spec-compliance-matrix/php.yaml
+++ b/spec-compliance-matrix/php.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/python.yaml b/spec-compliance-matrix/python.yaml
index 9c686be08a1..592a02cf991 100644
--- a/spec-compliance-matrix/python.yaml
+++ b/spec-compliance-matrix/python.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '-'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/ruby.yaml b/spec-compliance-matrix/ruby.yaml
index 0c690c00109..7acb5e6a3d3 100644
--- a/spec-compliance-matrix/ruby.yaml
+++ b/spec-compliance-matrix/ruby.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/rust.yaml b/spec-compliance-matrix/rust.yaml
index 1f3cb6913f3..c85d7f1eebb 100644
--- a/spec-compliance-matrix/rust.yaml
+++ b/spec-compliance-matrix/rust.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/swift.yaml b/spec-compliance-matrix/swift.yaml
index 5ff118465d6..5dde92f7475 100644
--- a/spec-compliance-matrix/swift.yaml
+++ b/spec-compliance-matrix/swift.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory OptIn parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/template.yaml b/spec-compliance-matrix/template.yaml
index 3013f98e178..ac6fba7c328 100644
--- a/spec-compliance-matrix/template.yaml
+++ b/spec-compliance-matrix/template.yaml
@@ -155,6 +155,7 @@ sections:
       - name: Instrument descriptions conform to the specified syntax.
       - name: Instrument supports the advisory ExplicitBucketBoundaries parameter.
       - name: Instrument supports the advisory Attributes parameter.
+      - name: Instrument supports the advisory OptIn parameter.
       - name: All methods of `MeterProvider` are safe to be called concurrently.
       - name: All methods of `Meter` are safe to be called concurrently.
       - name: All methods of any instrument are safe to be called concurrently.
diff --git a/specification/metrics/api.md b/specification/metrics/api.md
index c37fccc944d..7439b6ab9d4 100644
--- a/specification/metrics/api.md
+++ b/specification/metrics/api.md
@@ -26,6 +26,7 @@ weight: 1
     + [Instrument advisory parameters](#instrument-advisory-parameters)
       - [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
       - [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
+      - [Instrument advisory parameter: `OptIn`](#instrument-advisory-parameter-optin)
     + [Synchronous and Asynchronous instruments](#synchronous-and-asynchronous-instruments)
       - [Synchronous Instrument API](#synchronous-instrument-api)
       - [Asynchronous Instrument API](#asynchronous-instrument-api)
@@ -276,6 +277,16 @@ Applies to all instrument types.
 `Attributes` (a list of [attribute keys](../common/README.md#attribute)) is
 the recommended set of attribute keys to be used for the resulting metrics.
 
+##### Instrument advisory parameter: `OptIn`
+
+**Status**: [Development](../document-status.md)
+
+Applies to all instrument types.
+
+`OptIn` (bool) if true, indicates that the instrument MUST NOT
+produce metric data and that functions on the instrument SHOULD be no-ops
+unless the user has explicitly enabled the metric.
+
 #### Synchronous and Asynchronous instruments
 
 Instruments are categorized on whether they are synchronous or
diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index 0c3da4b83fc..96f5edccbf8 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -52,6 +52,7 @@ weight: 3
   * [Instrument advisory parameters](#instrument-advisory-parameters)
     + [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
     + [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
+    + [Instrument advisory parameter: `OptIn`](#instrument-advisory-parameter-optin)
   * [Instrument enabled](#instrument-enabled)
 - [Attribute limits](#attribute-limits)
 - [Exemplar](#exemplar)
@@ -413,6 +414,13 @@ The SDK MUST accept the following stream configuration parameters:
   `aggregation_cardinality_limit` value, the `MeterProvider` MUST apply the
   [default aggregation cardinality limit](#metricreader) the `MetricReader` is
   configured with.
+* **Status**: [Development](../document-status.md) - `enabled` (optional): A
+  boolean denoting whether the instrument should be enabled. When `enabled` is
+  `false`, the View uses the `DropAggregation`, regardless of the `aggregation`
+  provided. When `enabled` is `true` for an instrument with `OptIn` set to
+  `true`, the SDK treats the instrument as-if `OptIn` was set to false. The
+  SDK must allow `enabled` to be unset (neither true nor false). If unset,
+  `enabled` has no effect.
 
 #### Measurement processing
 
@@ -420,33 +428,36 @@ The SDK SHOULD use the following logic to determine how to process Measurements
 made with an Instrument:
 
 * Determine the `MeterProvider` which "owns" the Instrument.
-* If the `MeterProvider` has no `View` registered, take the Instrument
-    and apply the default Aggregation on the basis of instrument kind according
-    to the [MetricReader](#metricreader) instance's `aggregation` property.
+* If the `MeterProvider` has no `View` registered, or if the Instrument does
+  not match any View's instrument selection criteria:
+  * **Status**: [Development](../document-status.md) - If the instrument's
+    [OptIn advisory parameter](#instrument-advisory-parameter-optin)
+    is set to true, use the [Drop Aggregation](#drop-aggregation).
+  * If OptIn is false, take the Instrument and apply the default
+    Aggregation on the basis of instrument kind according to the
+    [MetricReader](#metricreader) instance's `aggregation` property.
     [Instrument advisory parameters](#instrument-advisory-parameters), if any,
     MUST be honored.
-* If the `MeterProvider` has one or more `View`(s) registered:
-  * If the Instrument could match the instrument selection criteria, for each
-    View:
-    * Try to apply the View's stream configuration independently of any other
-      Views registered for the same matching Instrument (i.e. Views are not
-      merged). This may result in [conflicting metric identities](./data-model.md#opentelemetry-protocol-data-model-producer-recommendations)
-      even if stream configurations specify non-overlapping properties (e.g.
-      one View setting `aggregation` and another View setting `attribute_keys`,
-      both leaving the stream `name` as the default configured by the
-      Instrument). If applying the View results in conflicting metric identities
-      the implementation SHOULD apply the View and emit a warning. If it is not
-      possible to apply the View without producing semantic errors (e.g. the
-      View sets an asynchronous instrument to use the [Explicit bucket
-      histogram aggregation](#explicit-bucket-histogram-aggregation)) the
-      implementation SHOULD emit a warning and proceed as if the View did not
-      If both a View and [Instrument advisory parameters](#instrument-advisory-parameters)
-      specify the same aspect of the [Stream configuration](#stream-configuration),
-      the setting defined by the View MUST take precedence over the advisory parameters.
-  * If the Instrument could not match with any of the registered `View`(s), the
-    SDK SHOULD enable the instrument using the default aggregation and temporality.
-    Users can configure match-all Views using [Drop aggregation](#drop-aggregation)
-    to disable instruments by default.
+* If the `MeterProvider` has one or more matching `View`(s) registered, for
+  each `View` that matches the instrument selection criteria:
+  * Try to apply the View's stream configuration independently of any other
+    Views registered for the same matching Instrument (i.e. Views are not
+    merged). This may result in [conflicting metric identities](./data-model.md#opentelemetry-protocol-data-model-producer-recommendations)
+    even if stream configurations specify non-overlapping properties (e.g.
+    one View setting `aggregation` and another View setting `attribute_keys`,
+    both leaving the stream `name` as the default configured by the
+    Instrument). If applying the View results in conflicting metric identities
+    the implementation SHOULD apply the View and emit a warning. If it is not
+    possible to apply the View without producing semantic errors (e.g. the
+    View sets an asynchronous instrument to use the [Explicit bucket
+    histogram aggregation](#explicit-bucket-histogram-aggregation)) the
+    implementation SHOULD emit a warning and proceed as if the View did not
+    If both a View and [Instrument advisory parameters](#instrument-advisory-parameters)
+    specify the same aspect of the [Stream configuration](#stream-configuration),
+    the setting defined by the View MUST take precedence over the advisory parameters.
+
+Users can configure match-all Views with `enabled=false` or with the
+[Drop aggregation](#drop-aggregation), to disable instruments by default.
 
 #### View examples
 
@@ -999,6 +1010,20 @@ If no View is configured, or if a matching view does not specify attribute keys,
 the advisory parameter should be used. If neither is provided, all attributes
 must be retained.
 
+#### Instrument advisory parameter: `OptIn`
+
+**Status**: [Development](../document-status.md)
+
+This advisory parameter applies to all aggregations.
+
+When an instrument has `OptIn=true`, the SDK MUST use the
+[Drop Aggregation](#drop-aggregation). If the user sets `enabled=true` on a
+View's [Stream configuration](#stream-configuration), this "enables" the
+instrument with the same behavior as-if the instrument was `OptIn=false` --
+including respecting other advisory parameters. Setting fields other than
+`enabled` on the View, including setting the `aggregation`, does not enable
+the instrument.
+
 ### Instrument enabled
 
 The synchronous instrument [`Enabled`](./api.md#enabled) MUST return `false`