diff --git a/.changesets/add-instrumentation-for-streaming-rack-responses.md b/.changesets/add-instrumentation-for-streaming-rack-responses.md
new file mode 100644
index 000000000..8d562cd85
--- /dev/null
+++ b/.changesets/add-instrumentation-for-streaming-rack-responses.md
@@ -0,0 +1,21 @@
+---
+bump: "minor"
+type: "add"
+---
+
+Add instrumentation to Rack responses, including streaming responses. New `process_response_body.rack` and `close_response_body.rack` events will be shown in the event timeline. These events show how long it takes to complete responses, depending on the response implementation, and when the response is closed.
+
+This Sinatra route with a streaming response will be better instrumented, for example:
+
+```ruby
+get "/stream" do
+  stream do |out|
+    sleep 1
+    out << "1"
+    sleep 1
+    out << "2"
+    sleep 1
+    out << "3"
+  end
+end
+```
diff --git a/lib/appsignal.rb b/lib/appsignal.rb
index 4e81e6222..4b096457a 100644
--- a/lib/appsignal.rb
+++ b/lib/appsignal.rb
@@ -325,6 +325,7 @@ def const_missing(name)
 require "appsignal/marker"
 require "appsignal/garbage_collection"
 require "appsignal/rack"
+require "appsignal/rack/body_wrapper"
 require "appsignal/rack/abstract_middleware"
 require "appsignal/rack/instrumentation_middleware"
 require "appsignal/rack/event_handler"
diff --git a/lib/appsignal/rack/abstract_middleware.rb b/lib/appsignal/rack/abstract_middleware.rb
index 26d976cb3..e2a197855 100644
--- a/lib/appsignal/rack/abstract_middleware.rb
+++ b/lib/appsignal/rack/abstract_middleware.rb
@@ -58,7 +58,7 @@ def call(env)
                 wrapped_instrumentation
               )
             else
-              instrument_app_call(request.env)
+              instrument_app_call(request.env, transaction)
             end
           ensure
             add_transaction_metadata_after(transaction, request)
@@ -81,16 +81,22 @@ def call(env)
       # stack and will report the exception and complete the transaction.
       #
       # @see {#instrument_app_call_with_exception_handling}
-      def instrument_app_call(env)
+      def instrument_app_call(env, transaction)
         if @instrument_event_name
           Appsignal.instrument(@instrument_event_name) do
-            @app.call(env)
+            call_app(env, transaction)
           end
         else
-          @app.call(env)
+          call_app(env, transaction)
         end
       end
 
+      def call_app(env, transaction)
+        status, headers, obody = @app.call(env)
+        # Instrument response body and closing of the response body
+        [status, headers, Appsignal::Rack::BodyWrapper.wrap(obody, transaction)]
+      end
+
       # Instrument the request fully. This is used by the top instrumentation
       # middleware in the middleware stack. Unlike
       # {#instrument_app_call} this will report any exceptions being
@@ -98,7 +104,7 @@ def instrument_app_call(env)
       #
       # @see {#instrument_app_call}
       def instrument_app_call_with_exception_handling(env, transaction, wrapped_instrumentation)
-        instrument_app_call(env)
+        instrument_app_call(env, transaction)
       rescue Exception => error # rubocop:disable Lint/RescueException
         report_errors =
           if @report_errors == DEFAULT_ERROR_REPORTING
diff --git a/lib/appsignal/rack/body_wrapper.rb b/lib/appsignal/rack/body_wrapper.rb
new file mode 100644
index 000000000..737b3bf7d
--- /dev/null
+++ b/lib/appsignal/rack/body_wrapper.rb
@@ -0,0 +1,143 @@
+# frozen_string_literal: true
+
+module Appsignal
+  module Rack
+    # @api private
+    class BodyWrapper
+      def self.wrap(original_body, appsignal_transaction)
+        # The logic of how Rack treats a response body differs based on which methods
+        # the body responds to. This means that to support the Rack 3.x spec in full
+        # we need to return a wrapper which matches the API of the wrapped body as closely
+        # as possible. Pick the wrapper from the most specific to the least specific.
+        # See https://github.com/rack/rack/blob/main/SPEC.rdoc#the-body-
+        #
+        # What is important is that our Body wrapper responds to the same methods Rack
+        # (or a webserver) would be checking and calling, and passes through that functionality
+        # to the original body.
+        #
+        # This comment https://github.com/rails/rails/pull/49627#issuecomment-1769802573
+        # is of particular interest to understand why this has to be somewhat complicated.
+        if original_body.respond_to?(:to_path)
+          PathableBodyWrapper.new(original_body, appsignal_transaction)
+        elsif original_body.respond_to?(:to_ary)
+          ArrayableBodyWrapper.new(original_body, appsignal_transaction)
+        elsif !original_body.respond_to?(:each) && original_body.respond_to?(:call)
+          # This body only supports #call, so we must be running a Rack 3 application
+          # It is possible that a body exposes both `each` and `call` in the hopes of
+          # being backwards-compatible with both Rack 3.x and Rack 2.x, however
+          # this is not going to work since the SPEC says that if both are available,
+          # `each` should be used and `call` should be ignored.
+          # So for that case we can drop to our default EnumerableBodyWrapper
+          CallableBodyWrapper.new(original_body, appsignal_transaction)
+        else
+          EnumerableBodyWrapper.new(original_body, appsignal_transaction)
+        end
+      end
+
+      def initialize(body, appsignal_transaction)
+        @body_already_closed = false
+        @body = body
+        @transaction = appsignal_transaction
+      end
+
+      # This must be present in all Rack bodies and will be called by the serving adapter
+      def close
+        # The @body_already_closed check is needed so that if `to_ary`
+        # of the body has already closed itself (as prescribed) we do not
+        # attempt to close it twice
+        if !@body_already_closed && @body.respond_to?(:close)
+          Appsignal.instrument("close_response_body.rack") { @body.close }
+        end
+        @body_already_closed = true
+      rescue Exception => error # rubocop:disable Lint/RescueException
+        @transaction.set_error(error)
+        raise error
+      end
+    end
+
+    # The standard Rack body wrapper which exposes "each" for iterating
+    # over the response body. This is supported across all 3 major Rack
+    # versions.
+    #
+    # @api private
+    class EnumerableBodyWrapper < BodyWrapper
+      def each(&blk)
+        # This is a workaround for the Rails bug when there was a bit too much
+        # eagerness in implementing to_ary, see:
+        # https://github.com/rails/rails/pull/44953
+        # https://github.com/rails/rails/pull/47092
+        # https://github.com/rails/rails/pull/49627
+        # https://github.com/rails/rails/issues/49588
+        # While the Rack SPEC does not mandate `each` to be callable
+        # in a blockless way it is still a good idea to have it in place.
+        return enum_for(:each) unless block_given?
+
+        Appsignal.instrument("process_response_body.rack", "Process Rack response body (#each)") do
+          @body.each(&blk)
+        end
+      rescue Exception => error # rubocop:disable Lint/RescueException
+        @transaction.set_error(error)
+        raise error
+      end
+    end
+
+    # The callable response bodies are a new Rack 3.x feature, and would not work
+    # with older Rack versions. They must not respond to `each` because
+    # "If it responds to each, you must call each and not call". This is why
+    # it inherits from BodyWrapper directly and not from EnumerableBodyWrapper
+    #
+    # @api private
+    class CallableBodyWrapper < BodyWrapper
+      def call(stream)
+        # `stream` will be closed by the app we are calling, no need for us
+        # to close it ourselves
+        Appsignal.instrument("process_response_body.rack", "Process Rack response body (#call)") do
+          @body.call(stream)
+        end
+      rescue Exception => error # rubocop:disable Lint/RescueException
+        @transaction.set_error(error)
+        raise error
+      end
+    end
+
+    # "to_ary" takes precedence over "each" and allows the response body
+    # to be read eagerly. If the body supports that method, it takes precedence
+    # over "each":
+    # "Middleware may call to_ary directly on the Body and return a new Body in its place"
+    # One could "fold" both the to_ary API and the each() API into one Body object, but
+    # to_ary must also call "close" after it executes - and in the Rails implementation
+    # this pecularity was not handled properly.
+    #
+    # @api private
+    class ArrayableBodyWrapper < EnumerableBodyWrapper
+      def to_ary
+        @body_already_closed = true
+        Appsignal.instrument(
+          "process_response_body.rack",
+          "Process Rack response body (#to_ary)"
+        ) do
+          @body.to_ary
+        end
+      rescue Exception => error # rubocop:disable Lint/RescueException
+        @transaction.set_error(error)
+        raise error
+      end
+    end
+
+    # Having "to_path" on a body allows Rack to serve out a static file, or to
+    # pass that file to the downstream webserver for sending using X-Sendfile
+    class PathableBodyWrapper < EnumerableBodyWrapper
+      def to_path
+        Appsignal.instrument(
+          "process_response_body.rack",
+          "Process Rack response body (#to_path)"
+        ) do
+          @body.to_path
+        end
+      rescue Exception => error # rubocop:disable Lint/RescueException
+        @transaction.set_error(error)
+        raise error
+      end
+    end
+  end
+end
diff --git a/spec/lib/appsignal/rack/abstract_middleware_spec.rb b/spec/lib/appsignal/rack/abstract_middleware_spec.rb
index 523591e53..a83663962 100644
--- a/spec/lib/appsignal/rack/abstract_middleware_spec.rb
+++ b/spec/lib/appsignal/rack/abstract_middleware_spec.rb
@@ -45,6 +45,11 @@ def make_request_with_error(error_class, error_message)
         expect(last_transaction).to have_namespace(Appsignal::Transaction::HTTP_REQUEST)
       end
 
+      it "wraps the response body in a BodyWrapper subclass" do
+        _status, _headers, body = make_request
+        expect(body).to be_kind_of(Appsignal::Rack::BodyWrapper)
+      end
+
       context "without an error" do
         before { make_request }
 
diff --git a/spec/lib/appsignal/rack/body_wrapper_spec.rb b/spec/lib/appsignal/rack/body_wrapper_spec.rb
new file mode 100644
index 000000000..3ac346271
--- /dev/null
+++ b/spec/lib/appsignal/rack/body_wrapper_spec.rb
@@ -0,0 +1,263 @@
+describe Appsignal::Rack::BodyWrapper do
+  let(:transaction) { http_request_transaction }
+  before do
+    start_agent
+    set_current_transaction(transaction)
+  end
+
+  describe "with a body that supports all possible features" do
+    it "reduces the supported methods to just each()" do
+      # which is the safest thing to do, since the body is likely broken
+      fake_body = double(
+        :each => nil,
+        :call => nil,
+        :to_ary => [],
+        :to_path => "/tmp/foo.bin",
+        :close => nil
+      )
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped).to respond_to(:each)
+      expect(wrapped).to_not respond_to(:to_ary)
+      expect(wrapped).to_not respond_to(:call)
+      expect(wrapped).to respond_to(:close)
+    end
+  end
+
+  describe "with a body only supporting each()" do
+    it "wraps with appropriate class" do
+      fake_body = double(:each => nil)
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped).to respond_to(:each)
+      expect(wrapped).to_not respond_to(:to_ary)
+      expect(wrapped).to_not respond_to(:call)
+      expect(wrapped).to respond_to(:close)
+    end
+
+    it "reads out the body in full using each" do
+      fake_body = double
+      expect(fake_body).to receive(:each).once.and_yield("a").and_yield("b").and_yield("c")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect { |b| wrapped.each(&b) }.to yield_successive_args("a", "b", "c")
+
+      expect(transaction).to include_event(
+        "name" => "process_response_body.rack",
+        "title" => "Process Rack response body (#each)"
+      )
+    end
+
+    it "returns an Enumerator if each() gets called without a block" do
+      fake_body = double
+      expect(fake_body).to receive(:each).once.and_yield("a").and_yield("b").and_yield("c")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      enum = wrapped.each
+      expect(enum).to be_kind_of(Enumerator)
+      expect { |b| enum.each(&b) }.to yield_successive_args("a", "b", "c")
+
+      expect(transaction).to_not include_event("name" => "process_response_body.rack")
+    end
+
+    it "sets the exception raised inside each() on the transaction" do
+      fake_body = double
+      expect(fake_body).to receive(:each).once.and_raise(ExampleException, "error message")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect do
+        expect { |b| wrapped.each(&b) }.to yield_control
+      end.to raise_error(ExampleException, "error message")
+
+      expect(transaction).to have_error("ExampleException", "error message")
+    end
+
+    it "closes the body and tracks an instrumentation event when it gets closed" do
+      fake_body = double(:close => nil)
+      expect(fake_body).to receive(:each).once.and_yield("a").and_yield("b").and_yield("c")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect { |b| wrapped.each(&b) }.to yield_successive_args("a", "b", "c")
+      wrapped.close
+
+      expect(transaction).to include_event("name" => "close_response_body.rack")
+    end
+  end
+
+  describe "with a body supporting both each() and call" do
+    it "wraps with the wrapper that conceals call() and exposes each" do
+      fake_body = double
+      allow(fake_body).to receive(:each)
+      allow(fake_body).to receive(:call)
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped).to respond_to(:each)
+      expect(wrapped).to_not respond_to(:to_ary)
+      expect(wrapped).to_not respond_to(:call)
+      expect(wrapped).to_not respond_to(:to_path)
+      expect(wrapped).to respond_to(:close)
+    end
+  end
+
+  describe "with a body supporting both to_ary and each" do
+    let(:fake_body) { double(:each => nil, :to_ary => []) }
+
+    it "wraps with appropriate class" do
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped).to respond_to(:each)
+      expect(wrapped).to respond_to(:to_ary)
+      expect(wrapped).to_not respond_to(:call)
+      expect(wrapped).to_not respond_to(:to_path)
+      expect(wrapped).to respond_to(:close)
+    end
+
+    it "reads out the body in full using each" do
+      expect(fake_body).to receive(:each).once.and_yield("a").and_yield("b").and_yield("c")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect { |b| wrapped.each(&b) }.to yield_successive_args("a", "b", "c")
+
+      expect(transaction).to include_event(
+        "name" => "process_response_body.rack",
+        "title" => "Process Rack response body (#each)"
+      )
+    end
+
+    it "sets the exception raised inside each() into the Appsignal transaction" do
+      expect(fake_body).to receive(:each).once.and_raise(ExampleException, "error message")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect do
+        expect { |b| wrapped.each(&b) }.to yield_control
+      end.to raise_error(ExampleException, "error message")
+
+      expect(transaction).to have_error("ExampleException", "error message")
+    end
+
+    it "reads out the body in full using to_ary" do
+      expect(fake_body).to receive(:to_ary).and_return(["one", "two", "three"])
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped.to_ary).to eq(["one", "two", "three"])
+
+      expect(transaction).to include_event(
+        "name" => "process_response_body.rack",
+        "title" => "Process Rack response body (#to_ary)"
+      )
+    end
+
+    it "sends the exception raised inside to_ary() into the Appsignal and closes transaction" do
+      fake_body = double
+      allow(fake_body).to receive(:each)
+      expect(fake_body).to receive(:to_ary).once.and_raise(ExampleException, "error message")
+      expect(fake_body).to_not receive(:close) # Per spec we expect the body has closed itself
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect do
+        wrapped.to_ary
+      end.to raise_error(ExampleException, "error message")
+
+      expect(transaction).to have_error("ExampleException", "error message")
+    end
+  end
+
+  describe "with a body supporting both to_path and each" do
+    let(:fake_body) { double(:each => nil, :to_path => nil) }
+
+    it "wraps with appropriate class" do
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped).to respond_to(:each)
+      expect(wrapped).to_not respond_to(:to_ary)
+      expect(wrapped).to_not respond_to(:call)
+      expect(wrapped).to respond_to(:to_path)
+      expect(wrapped).to respond_to(:close)
+    end
+
+    it "reads out the body in full using each()" do
+      expect(fake_body).to receive(:each).once.and_yield("a").and_yield("b").and_yield("c")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect { |b| wrapped.each(&b) }.to yield_successive_args("a", "b", "c")
+
+      expect(transaction).to include_event(
+        "name" => "process_response_body.rack",
+        "title" => "Process Rack response body (#each)"
+      )
+    end
+
+    it "sets the exception raised inside each() into the Appsignal transaction" do
+      expect(fake_body).to receive(:each).once.and_raise(ExampleException, "error message")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect do
+        expect { |b| wrapped.each(&b) }.to yield_control
+      end.to raise_error(ExampleException, "error message")
+
+      expect(transaction).to have_error("ExampleException", "error message")
+    end
+
+    it "sets the exception raised inside to_path() into the Appsignal transaction" do
+      allow(fake_body).to receive(:to_path).once.and_raise(ExampleException, "error message")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect do
+        wrapped.to_path
+      end.to raise_error(ExampleException, "error message")
+
+      expect(transaction).to have_error("ExampleException", "error message")
+    end
+
+    it "exposes to_path to the sender" do
+      allow(fake_body).to receive(:to_path).and_return("/tmp/file.bin")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped.to_path).to eq("/tmp/file.bin")
+
+      expect(transaction).to include_event(
+        "name" => "process_response_body.rack",
+        "title" => "Process Rack response body (#to_path)"
+      )
+    end
+  end
+
+  describe "with a body only supporting call()" do
+    let(:fake_body) { double(:call => nil) }
+
+    it "wraps with appropriate class" do
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect(wrapped).to_not respond_to(:each)
+      expect(wrapped).to_not respond_to(:to_ary)
+      expect(wrapped).to respond_to(:call)
+      expect(wrapped).to_not respond_to(:to_path)
+      expect(wrapped).to respond_to(:close)
+    end
+
+    it "passes the stream into the call() of the body" do
+      fake_rack_stream = double("stream")
+      expect(fake_body).to receive(:call).with(fake_rack_stream)
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      wrapped.call(fake_rack_stream)
+
+      expect(transaction).to include_event(
+        "name" => "process_response_body.rack",
+        "title" => "Process Rack response body (#call)"
+      )
+    end
+
+    it "sets the exception raised inside call() into the Appsignal transaction" do
+      fake_rack_stream = double
+      allow(fake_body).to receive(:call)
+        .with(fake_rack_stream)
+        .and_raise(ExampleException, "error message")
+
+      wrapped = described_class.wrap(fake_body, transaction)
+
+      expect do
+        wrapped.call(fake_rack_stream)
+      end.to raise_error(ExampleException, "error message")
+
+      expect(transaction).to have_error("ExampleException", "error message")
+    end
+  end
+end