diff --git a/assert_changes_second_argument.patch b/assert_changes_second_argument.patch
new file mode 100644
index 0000000000..3b7af402ad
--- /dev/null
+++ b/assert_changes_second_argument.patch
@@ -0,0 +1,207 @@
+diff --git a/changelog/new_assert_changes_second_argument_cop.md b/changelog/new_assert_changes_second_argument_cop.md
+new file mode 100644
+index 000000000..179ffc586
+--- /dev/null
++++ b/changelog/new_assert_changes_second_argument_cop.md
+@@ -0,0 +1 @@
++* [#1396](https://github.com/rubocop/rubocop-rails/issues/1396): Add cop to prevent use of assert_changes with non-string second arguments. ([@joseph-carino][])
+diff --git a/config/default.yml b/config/default.yml
+index 0e7d18346..c9759fca8 100644
+--- a/config/default.yml
++++ b/config/default.yml
+@@ -222,6 +222,13 @@ Rails/ArelStar:
+   SafeAutoCorrect: false
+   VersionAdded: '2.9'
+ 
++Rails/AssertChangesSecondArgument:
++  Description: 'Do not use `assert_changes` with a non-string second argument.'
++  Enabled: true
++  VersionAdded: '2.28'
++  Include:
++    - '**/test/**/*'
++
+ Rails/AssertNot:
+   Description: 'Use `assert_not` instead of `assert !`.'
+   Enabled: true
+diff --git a/lib/rubocop/cop/rails/assert_changes_second_argument.rb b/lib/rubocop/cop/rails/assert_changes_second_argument.rb
+new file mode 100644
+index 000000000..2adc3c930
+--- /dev/null
++++ b/lib/rubocop/cop/rails/assert_changes_second_argument.rb
+@@ -0,0 +1,63 @@
++# frozen_string_literal: true
++
++module RuboCop
++  module Cop
++    module Rails
++      # Checks misuse of the second argument to ActiveSupport `assert_changes` method
++      #
++      # `assert_changes`'s second argument is the failure message emitted when the
++      # first argument (expression) is unchanged in the block.
++      #
++      # A common mistake is to use `assert_changes` with the expected change
++      # value delta as the second argument.
++      # In that case `assert_changes` will validate only that the expression changes,
++      # not that it changes by a specific value.
++      #
++      # Users should provide the 'from' and 'to' parameters,
++      # or use `assert_difference` instead, which does support deltas.
++      #
++      # @example
++      #
++      #   # bad
++      #   assert_changes -> { @value }, 1 do
++      #     @value += 1
++      #   end
++      #
++      #   # good
++      #   assert_changes -> { @value }, from: 0, to: 1 do
++      #     @value += 1
++      #   end
++      #   assert_changes -> { @value }, "Value should change" do
++      #     @value += 1
++      #   end
++      #   assert_difference -> { @value }, 1 do
++      #     @value += 1
++      #   end
++      #
++      class AssertChangesSecondArgument < Base
++        extend AutoCorrector
++
++        MSG = 'Use assert_changes to assert when an expression changes from and to specific values. ' \
++              'Use assert_difference instead to assert when an expression changes by a specific delta. ' \
++              'The second argument to assert_changes is the message emitted on assert failure.'
++
++        def on_send(node)
++          return if node.receiver || !node.method?(:assert_changes)
++          return if node.arguments[1].nil?
++
++          return unless offense?(node.arguments[1])
++
++          add_offense(node.loc.selector) do |corrector|
++            corrector.replace(node.loc.selector, 'assert_difference')
++          end
++        end
++
++        private
++
++        def offense?(arg)
++          !arg.hash_type? && !arg.str_type? && !arg.dstr_type? && !arg.sym_type? && !arg.dsym_type?
++        end
++      end
++    end
++  end
++end
+diff --git a/lib/rubocop/cop/rails_cops.rb b/lib/rubocop/cop/rails_cops.rb
+index b7eddc4fe..b862ffc9d 100644
+--- a/lib/rubocop/cop/rails_cops.rb
++++ b/lib/rubocop/cop/rails_cops.rb
+@@ -25,6 +25,7 @@ require_relative 'rails/application_job'
+ require_relative 'rails/application_mailer'
+ require_relative 'rails/application_record'
+ require_relative 'rails/arel_star'
++require_relative 'rails/assert_changes_second_argument'
+ require_relative 'rails/assert_not'
+ require_relative 'rails/attribute_default_block_value'
+ require_relative 'rails/belongs_to'
+diff --git a/spec/rubocop/cop/rails/assert_changes_second_argument_spec.rb b/spec/rubocop/cop/rails/assert_changes_second_argument_spec.rb
+new file mode 100644
+index 000000000..f832b8076
+--- /dev/null
++++ b/spec/rubocop/cop/rails/assert_changes_second_argument_spec.rb
+@@ -0,0 +1,95 @@
++# frozen_string_literal: true
++
++RSpec.describe(RuboCop::Cop::Rails::AssertChangesSecondArgument, :config) do
++  let(:message) do
++    'Use assert_changes to assert when an expression changes from and to specific values. ' \
++      'Use assert_difference instead to assert when an expression changes by a specific delta. ' \
++      'The second argument to assert_changes is the message emitted on assert failure.'
++  end
++
++  describe('offenses') do
++    it 'adds offense when the second positional argument is an integer' do
++      expect_offense(<<~RUBY)
++        assert_changes @value, -1 do
++        ^^^^^^^^^^^^^^ #{message}
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'adds offense when the second positional argument is a float' do
++      expect_offense(<<~RUBY)
++        assert_changes @value, -1.0 do
++        ^^^^^^^^^^^^^^ #{message}
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'does not add offense when the second argument is a string' do
++      expect_no_offenses(<<~RUBY)
++        assert_changes @value, "Value should change" do
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'does not add offense when the second argument is an interpolated string' do
++      expect_no_offenses(<<~RUBY)
++        assert_changes @value, "\#{thing} should change" do
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'does not add offense when the second argument is a symbol' do
++      expect_no_offenses(<<~RUBY)
++        assert_changes @value, :should_change do
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'does not add offense when the second argument is an interpolated symbol' do
++      expect_no_offenses(<<~RUBY)
++        assert_changes @value, :"\#{thing}_should_change" do
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'does not add offense when there is only one argument' do
++      expect_no_offenses(<<~RUBY)
++        assert_changes @value do
++          @value += 1
++        end
++      RUBY
++    end
++
++    it 'does not add offense when there is only one positional argument' do
++      expect_no_offenses(<<~RUBY)
++        assert_changes @value, from: 0 do
++          @value += 1
++        end
++      RUBY
++    end
++  end
++
++  describe('autocorrect') do
++    it 'autocorrects method from assert_changes to assert_difference' do
++      source = <<-RUBY
++        assert_changes @value, -1.0 do
++          @value += 1
++        end
++      RUBY
++
++      corrected_source = <<-RUBY
++        assert_difference @value, -1.0 do
++          @value += 1
++        end
++      RUBY
++
++      expect(autocorrect_source(source)).to(eq(corrected_source))
++    end
++  end
++end
diff --git a/changelog/new_assert_changes_second_argument_cop.md b/changelog/new_assert_changes_second_argument_cop.md
new file mode 100644
index 0000000000..179ffc586e
--- /dev/null
+++ b/changelog/new_assert_changes_second_argument_cop.md
@@ -0,0 +1 @@
+* [#1396](https://github.com/rubocop/rubocop-rails/issues/1396): Add cop to prevent use of assert_changes with non-string second arguments. ([@joseph-carino][])
diff --git a/config/default.yml b/config/default.yml
index 0e7d183460..c9759fca82 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -222,6 +222,13 @@ Rails/ArelStar:
   SafeAutoCorrect: false
   VersionAdded: '2.9'
 
+Rails/AssertChangesSecondArgument:
+  Description: 'Do not use `assert_changes` with a non-string second argument.'
+  Enabled: true
+  VersionAdded: '2.28'
+  Include:
+    - '**/test/**/*'
+
 Rails/AssertNot:
   Description: 'Use `assert_not` instead of `assert !`.'
   Enabled: true
diff --git a/lib/rubocop/cop/rails/assert_changes_second_argument.rb b/lib/rubocop/cop/rails/assert_changes_second_argument.rb
new file mode 100644
index 0000000000..2adc3c9301
--- /dev/null
+++ b/lib/rubocop/cop/rails/assert_changes_second_argument.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # Checks misuse of the second argument to ActiveSupport `assert_changes` method
+      #
+      # `assert_changes`'s second argument is the failure message emitted when the
+      # first argument (expression) is unchanged in the block.
+      #
+      # A common mistake is to use `assert_changes` with the expected change
+      # value delta as the second argument.
+      # In that case `assert_changes` will validate only that the expression changes,
+      # not that it changes by a specific value.
+      #
+      # Users should provide the 'from' and 'to' parameters,
+      # or use `assert_difference` instead, which does support deltas.
+      #
+      # @example
+      #
+      #   # bad
+      #   assert_changes -> { @value }, 1 do
+      #     @value += 1
+      #   end
+      #
+      #   # good
+      #   assert_changes -> { @value }, from: 0, to: 1 do
+      #     @value += 1
+      #   end
+      #   assert_changes -> { @value }, "Value should change" do
+      #     @value += 1
+      #   end
+      #   assert_difference -> { @value }, 1 do
+      #     @value += 1
+      #   end
+      #
+      class AssertChangesSecondArgument < Base
+        extend AutoCorrector
+
+        MSG = 'Use assert_changes to assert when an expression changes from and to specific values. ' \
+              'Use assert_difference instead to assert when an expression changes by a specific delta. ' \
+              'The second argument to assert_changes is the message emitted on assert failure.'
+
+        def on_send(node)
+          return if node.receiver || !node.method?(:assert_changes)
+          return if node.arguments[1].nil?
+
+          return unless offense?(node.arguments[1])
+
+          add_offense(node.loc.selector) do |corrector|
+            corrector.replace(node.loc.selector, 'assert_difference')
+          end
+        end
+
+        private
+
+        def offense?(arg)
+          !arg.hash_type? && !arg.str_type? && !arg.dstr_type? && !arg.sym_type? && !arg.dsym_type?
+        end
+      end
+    end
+  end
+end
diff --git a/lib/rubocop/cop/rails_cops.rb b/lib/rubocop/cop/rails_cops.rb
index b7eddc4fe4..b862ffc9da 100644
--- a/lib/rubocop/cop/rails_cops.rb
+++ b/lib/rubocop/cop/rails_cops.rb
@@ -25,6 +25,7 @@
 require_relative 'rails/application_mailer'
 require_relative 'rails/application_record'
 require_relative 'rails/arel_star'
+require_relative 'rails/assert_changes_second_argument'
 require_relative 'rails/assert_not'
 require_relative 'rails/attribute_default_block_value'
 require_relative 'rails/belongs_to'
diff --git a/spec/rubocop/cop/rails/assert_changes_second_argument_spec.rb b/spec/rubocop/cop/rails/assert_changes_second_argument_spec.rb
new file mode 100644
index 0000000000..f832b80767
--- /dev/null
+++ b/spec/rubocop/cop/rails/assert_changes_second_argument_spec.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+RSpec.describe(RuboCop::Cop::Rails::AssertChangesSecondArgument, :config) do
+  let(:message) do
+    'Use assert_changes to assert when an expression changes from and to specific values. ' \
+      'Use assert_difference instead to assert when an expression changes by a specific delta. ' \
+      'The second argument to assert_changes is the message emitted on assert failure.'
+  end
+
+  describe('offenses') do
+    it 'adds offense when the second positional argument is an integer' do
+      expect_offense(<<~RUBY)
+        assert_changes @value, -1 do
+        ^^^^^^^^^^^^^^ #{message}
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'adds offense when the second positional argument is a float' do
+      expect_offense(<<~RUBY)
+        assert_changes @value, -1.0 do
+        ^^^^^^^^^^^^^^ #{message}
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'does not add offense when the second argument is a string' do
+      expect_no_offenses(<<~RUBY)
+        assert_changes @value, "Value should change" do
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'does not add offense when the second argument is an interpolated string' do
+      expect_no_offenses(<<~RUBY)
+        assert_changes @value, "\#{thing} should change" do
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'does not add offense when the second argument is a symbol' do
+      expect_no_offenses(<<~RUBY)
+        assert_changes @value, :should_change do
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'does not add offense when the second argument is an interpolated symbol' do
+      expect_no_offenses(<<~RUBY)
+        assert_changes @value, :"\#{thing}_should_change" do
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'does not add offense when there is only one argument' do
+      expect_no_offenses(<<~RUBY)
+        assert_changes @value do
+          @value += 1
+        end
+      RUBY
+    end
+
+    it 'does not add offense when there is only one positional argument' do
+      expect_no_offenses(<<~RUBY)
+        assert_changes @value, from: 0 do
+          @value += 1
+        end
+      RUBY
+    end
+  end
+
+  describe('autocorrect') do
+    it 'autocorrects method from assert_changes to assert_difference' do
+      source = <<-RUBY
+        assert_changes @value, -1.0 do
+          @value += 1
+        end
+      RUBY
+
+      corrected_source = <<-RUBY
+        assert_difference @value, -1.0 do
+          @value += 1
+        end
+      RUBY
+
+      expect(autocorrect_source(source)).to(eq(corrected_source))
+    end
+  end
+end