diff --git a/CHANGELOG.md b/CHANGELOG.md
index 94fd9ca7..1033f67c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
   * `AdditionalOperationsBefore32`: detect Path Item `additionalOperations` usage in pre-3.2 documents (3.2 addition)
   * `QuerystringBefore32`: detect Parameter `in: querystring` usage in pre-3.2 documents (3.2 addition; not validated at runtime)
   * `CookieStyleBefore32`: detect Parameter `style: cookie` usage in pre-3.2 documents (3.2 addition)
+  * `ResponseSummaryBefore32`: detect Response Object `summary` usage in pre-3.2 documents (3.2 addition)
 * validate a value against a schema without `type`: keywords such as `properties`, `required`, `items`, `maxLength`, `enum` and `minimum` now apply when the value has the type the keyword is for, as in JSON Schema. They were all skipped before, so a value that breaks them may now fail validation
 * add `allow_3_2_features` config to apply OpenAPI 3.2 runtime behavior to documents that declare an earlier version (default `false`: pre-3.2 documents behave as before)
 * support `components.mediaTypes` (OpenAPI 3.2), resolving `$ref`s in request body and response `content` in 3.2 documents; an unresolved one accepts any body unless `strict_reference_validation` is set
@@ -20,6 +21,7 @@
 * support Discriminator `defaultMapping` (OpenAPI 3.2): fallback schema when the discriminator property is absent or its value has no explicit or implicit mapping; honored in 3.2 documents
 * support the `query` HTTP method and `additionalOperations` (OpenAPI 3.2) on Path Items, including request-operation lookup, in 3.2 documents
 * match HTTP methods case-insensitively in request-operation lookup in 3.2 documents (`request_operation("GET", path)` still returns nil before 3.2)
+* support Response Object `summary` (OpenAPI 3.2) in the parse layer
 
 ## 2.5.0 (2026-10-21)
 * add OpenAPI 3.2 `SpecValidator` rules
diff --git a/lib/openapi_parser/schemas/response.rb b/lib/openapi_parser/schemas/response.rb
index c203c995..e17c9f99 100644
--- a/lib/openapi_parser/schemas/response.rb
+++ b/lib/openapi_parser/schemas/response.rb
@@ -6,6 +6,10 @@ class Response < Base
 
     openapi_attr_values :description
 
+    # @!attribute [r] summary
+    #   @return [String, nil] short summary of the response (OpenAPI 3.2+)
+    openapi_attr_value :summary
+
     # @!attribute [r] content
     #   @return [Hash{String => MediaType}, nil] content_type to MediaType hash
     openapi_attr_hash_object :content, MediaType, reference: OpenAPIParser::MediaTypeSelectable::CONTENT_REFERENCE
diff --git a/lib/openapi_parser/spec_validator.rb b/lib/openapi_parser/spec_validator.rb
index 129b9624..72ca0310 100644
--- a/lib/openapi_parser/spec_validator.rb
+++ b/lib/openapi_parser/spec_validator.rb
@@ -32,6 +32,7 @@
 require_relative 'spec_validator/rules/additional_operations_before_32'
 require_relative 'spec_validator/rules/querystring_before_32'
 require_relative 'spec_validator/rules/cookie_style_before_32'
+require_relative 'spec_validator/rules/response_summary_before_32'
 
 module OpenAPIParser
   class SpecViolationError < OpenAPIError
@@ -111,6 +112,7 @@ def rules
           Rules::AdditionalOperationsBefore32,
           Rules::QuerystringBefore32,
           Rules::CookieStyleBefore32,
+          Rules::ResponseSummaryBefore32,
         ]
       end
   end
diff --git a/lib/openapi_parser/spec_validator/rules/response_summary_before_32.rb b/lib/openapi_parser/spec_validator/rules/response_summary_before_32.rb
new file mode 100644
index 00000000..f3573f6a
--- /dev/null
+++ b/lib/openapi_parser/spec_validator/rules/response_summary_before_32.rb
@@ -0,0 +1,25 @@
+module OpenAPIParser
+  class SpecValidator
+    module Rules
+      # 3.2 adds `summary` to the Response Object. The parse layer accepts it
+      # permissively; this rule reports the version mismatch.
+      class ResponseSummaryBefore32 < Rule
+        def check(root)
+          return [] unless version_before?('3.2')
+
+          violations = []
+          each_node(root, OpenAPIParser::Schemas::Response) do |node|
+            raw = node.raw_schema
+            next unless raw.is_a?(Hash) && raw.key?('summary')
+
+            violations << violation(
+              path: "#{node.object_reference}/summary",
+              message: '`summary` on a Response Object is a 3.2 addition; earlier documents have no such field',
+            )
+          end
+          violations
+        end
+      end
+    end
+  end
+end
diff --git a/sig/openapi_parser/spec_validator.rbs b/sig/openapi_parser/spec_validator.rbs
index 2c635479..23ac6376 100644
--- a/sig/openapi_parser/spec_validator.rbs
+++ b/sig/openapi_parser/spec_validator.rbs
@@ -175,6 +175,10 @@ module OpenAPIParser
       class CookieStyleBefore32 < Rule
         def check: (OpenAPIParser::Schemas::OpenAPI root) -> Array[SpecValidator::SpecViolation]
       end
+
+      class ResponseSummaryBefore32 < Rule
+        def check: (OpenAPIParser::Schemas::OpenAPI root) -> Array[SpecValidator::SpecViolation]
+      end
     end
   end
 
diff --git a/spec/data/openapi_3_2/response_summary_31.yaml b/spec/data/openapi_3_2/response_summary_31.yaml
new file mode 100644
index 00000000..19e32932
--- /dev/null
+++ b/spec/data/openapi_3_2/response_summary_31.yaml
@@ -0,0 +1,14 @@
+openapi: 3.1.0
+info:
+  title: Pet API
+  version: '1.0'
+paths:
+  /pets:
+    get:
+      summary: List pets
+      responses:
+        '200':
+          # `summary` on a Response Object is a 3.2 addition; a 3.1 document
+          # has no such field, so its use here is a spec violation.
+          summary: Pets
+          description: OK
diff --git a/spec/data/openapi_3_2/response_summary_32.yaml b/spec/data/openapi_3_2/response_summary_32.yaml
new file mode 100644
index 00000000..7792516a
--- /dev/null
+++ b/spec/data/openapi_3_2/response_summary_32.yaml
@@ -0,0 +1,12 @@
+openapi: 3.2.0
+info:
+  title: Pet API
+  version: '1.0'
+paths:
+  /pets:
+    get:
+      summary: List pets
+      responses:
+        '200':
+          summary: Pets
+          description: OK
diff --git a/spec/openapi_parser/schemas/response_spec.rb b/spec/openapi_parser/schemas/response_spec.rb
index 1c4f1165..74a21985 100644
--- a/spec/openapi_parser/schemas/response_spec.rb
+++ b/spec/openapi_parser/schemas/response_spec.rb
@@ -23,4 +23,13 @@
       expect(subject.content['application/json'].object_reference).to eq '#/paths/~1pets/get/responses/default/content/application~1json'
     end
   end
+
+  describe 'summary (OpenAPI 3.2)' do
+    let(:root) { OpenAPIParser.parse(load_yaml_file('./spec/data/openapi_3_2/response_summary_32.yaml'), {}) }
+
+    it 'is parsed onto the Response object' do
+      response = root.paths.path['/pets'].get.responses.response['200']
+      expect(response.summary).to eq 'Pets'
+    end
+  end
 end
diff --git a/spec/openapi_parser/spec_validator/integration_3_2_spec.rb b/spec/openapi_parser/spec_validator/integration_3_2_spec.rb
index 33c3d754..39b771a6 100644
--- a/spec/openapi_parser/spec_validator/integration_3_2_spec.rb
+++ b/spec/openapi_parser/spec_validator/integration_3_2_spec.rb
@@ -234,4 +234,18 @@ def expect_clean(file)
       expect_clean('cookie_style_32.yaml')
     end
   end
+
+  describe 'Response Object summary (3.2 addition)' do
+    it 'warns on the version-mismatched document under :warn' do
+      expect_mismatch_warns('response_summary_31.yaml', [:response_summary_before32])
+    end
+
+    it 'raises SpecViolationError on the version-mismatched document under :raise' do
+      expect_mismatch_raises('response_summary_31.yaml', [:response_summary_before32])
+    end
+
+    it 'stays clean on the correctly-versioned document' do
+      expect_clean('response_summary_32.yaml')
+    end
+  end
 end
diff --git a/spec/openapi_parser/spec_validator/rules/response_summary_before_32_spec.rb b/spec/openapi_parser/spec_validator/rules/response_summary_before_32_spec.rb
new file mode 100644
index 00000000..7e34748b
--- /dev/null
+++ b/spec/openapi_parser/spec_validator/rules/response_summary_before_32_spec.rb
@@ -0,0 +1,68 @@
+require_relative '../../../spec_helper'
+
+RSpec.describe 'OpenAPIParser::SpecValidator::Rules::ResponseSummaryBefore32' do
+  def base_doc(openapi_version_string, resp)
+    {
+      'openapi' => openapi_version_string,
+      'info' => { 'title' => 'test', 'version' => '1.0' },
+      'paths' => {
+        '/pets' => {
+          'get' => {
+            'responses' => { '200' => resp },
+          },
+        },
+      },
+    }
+  end
+
+  def doc_with(openapi_version_string)
+    OpenAPIParser.parse(base_doc(openapi_version_string, { 'summary' => 'Pets', 'description' => 'OK' }), strict_reference_validation: false)
+  end
+
+  def doc_without(openapi_version_string)
+    OpenAPIParser.parse(base_doc(openapi_version_string, { 'description' => 'OK' }), strict_reference_validation: false)
+  end
+
+  def run_rule_for(root)
+    OpenAPIParser::SpecValidator::Rules::ResponseSummaryBefore32.new(root.openapi_version).check(root)
+  end
+
+  context 'with a 3.2 document using a response summary' do
+    it 'reports no violation' do
+      expect(run_rule_for(doc_with('3.2.0'))).to eq []
+    end
+  end
+
+  context 'with a 3.2 document without a response summary' do
+    it 'reports no violation' do
+      expect(run_rule_for(doc_without('3.2.0'))).to eq []
+    end
+  end
+
+  context 'with a 3.1 document using a response summary' do
+    it 'reports one violation pointing at the field' do
+      violations = run_rule_for(doc_with('3.1.0'))
+      expect(violations.size).to eq 1
+      expect(violations.first.path).to eq '#/paths/~1pets/get/responses/200/summary'
+      expect(violations.first.rule_name).to eq :response_summary_before32
+    end
+  end
+
+  context 'with a 3.1 document without a response summary' do
+    it 'reports no violation' do
+      expect(run_rule_for(doc_without('3.1.0'))).to eq []
+    end
+  end
+
+  context 'with a 3.0 document using a response summary' do
+    it 'reports one violation' do
+      expect(run_rule_for(doc_with('3.0.0')).size).to eq 1
+    end
+  end
+
+  context 'with a document whose openapi field is not a version' do
+    it 'reports no violation (rule skipped)' do
+      expect(run_rule_for(doc_with('not-a-version'))).to eq []
+    end
+  end
+end