diff --git a/lib/hbc/cli.rb b/lib/hbc/cli.rb
index 91aaa03b348bb..83542f3d04424 100644
--- a/lib/hbc/cli.rb
+++ b/lib/hbc/cli.rb
@@ -16,6 +16,7 @@ class Hbc::CLI; end
 require 'hbc/cli/info'
 require 'hbc/cli/install'
 require 'hbc/cli/list'
+require 'hbc/cli/outdated'
 require 'hbc/cli/search'
 require 'hbc/cli/uninstall'
 require 'hbc/cli/update'
diff --git a/lib/hbc/cli/outdated.rb b/lib/hbc/cli/outdated.rb
new file mode 100644
index 0000000000000..ea49796a46db6
--- /dev/null
+++ b/lib/hbc/cli/outdated.rb
@@ -0,0 +1,9 @@
+class Hbc::CLI::Outdated < Hbc::CLI::Base
+  def self.help
+    'lists installed casks that have an upgraded version available'
+  end
+
+  def self.run(*args)
+    puts Hbc.outdated.map(&:to_s)
+  end
+end
diff --git a/lib/hbc/scopes.rb b/lib/hbc/scopes.rb
index d0489738fb1fc..ab0c1b33a1f7e 100644
--- a/lib/hbc/scopes.rb
+++ b/lib/hbc/scopes.rb
@@ -20,12 +20,6 @@ def all_tapped_cask_dirs
       @all_tapped_cask_dirs
     end
 
-    def reset_all_tapped_cask_dirs
-      # The memoized value should be reset when a Tap is added/removed
-      # (which is a rare event in our codebase).
-      @all_tapped_cask_dirs = nil
-    end
-
     def all_tokens
       cask_tokens = all_tapped_cask_dirs.map { |d| Dir.glob d.join('*.rb') }.flatten
       cask_tokens.map { |c|
@@ -58,5 +52,9 @@ def installed
         end
       end
     end
+
+    def outdated
+      installed.select(&:outdated?)
+    end
   end
 end
diff --git a/spec/cask/cli/outdated_spec.rb b/spec/cask/cli/outdated_spec.rb
new file mode 100644
index 0000000000000..8f7380d23a9d0
--- /dev/null
+++ b/spec/cask/cli/outdated_spec.rb
@@ -0,0 +1,27 @@
+require 'spec_helper'
+
+describe Hbc::CLI::Outdated do
+  describe '.help' do
+    it 'describes outdated properly' do
+      expect(described_class.help).to eq('lists installed casks that have an upgraded version available')
+    end
+  end
+
+  describe '.run' do
+    let(:outdated_casks) {[
+      double('Cask', to_s: 'pretty-old'),
+      double('Cask', to_s: 'cask-needs-upgrade-badly'),
+    ]}
+    before do
+      allow(Hbc).to receive(:outdated) { outdated_casks }
+    end
+    it 'lists the outdated casks' do
+      expect {
+        described_class.run
+      }.to output(<<-OUTPUT.gsub(/ */, '')).to_stdout
+        pretty-old
+        cask-needs-upgrade-badly
+      OUTPUT
+    end
+  end
+end
diff --git a/spec/cask/scopes_spec.rb b/spec/cask/scopes_spec.rb
index 602a6d79e5d32..db30a1ea35e81 100644
--- a/spec/cask/scopes_spec.rb
+++ b/spec/cask/scopes_spec.rb
@@ -41,4 +41,18 @@
       expect(Hbc).to have_received(:load).with(absolute_path_to_cask)
     end
   end
+
+  describe 'outdated' do
+    let(:installed_casks) {[
+      double('Cask', name: 'up-to-date', outdated?: false),
+      double('Cask', name: 'pretty-old', outdated?: true),
+    ]}
+    before do
+      allow(Hbc).to receive(:installed) { installed_casks }
+    end
+
+    it 'returns the list of casks whose installed version does not match the latest available version' do
+      expect(Hbc.outdated.map(&:name)).to eq(%w[pretty-old])
+    end
+  end
 end