diff --git a/contract-tests/service.rb b/contract-tests/service.rb
index 954715ee..dc5705e5 100644
--- a/contract-tests/service.rb
+++ b/contract-tests/service.rb
@@ -34,6 +34,7 @@
       'secure-mode-hash',
       'tags',
       'migrations',
+      'event-gzip',
       'event-sampling',
       'context-comparison',
       'polling-gzip',
diff --git a/launchdarkly-server-sdk.gemspec b/launchdarkly-server-sdk.gemspec
index be94a681..26c73c8d 100644
--- a/launchdarkly-server-sdk.gemspec
+++ b/launchdarkly-server-sdk.gemspec
@@ -39,6 +39,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "concurrent-ruby", "~> 1.1"
   spec.add_runtime_dependency "ld-eventsource", "2.2.2"
   spec.add_runtime_dependency "observer", "~> 0.1.2"
+  spec.add_runtime_dependency "zlib", "~> 3.1" unless RUBY_PLATFORM == "java"
   # Please keep ld-eventsource dependency as an exact version so that bugfixes to
   # that LD library are always associated with a new SDK version.
 
diff --git a/lib/ldclient-rb/impl/event_sender.rb b/lib/ldclient-rb/impl/event_sender.rb
index 4f4561d6..4fcdaf13 100644
--- a/lib/ldclient-rb/impl/event_sender.rb
+++ b/lib/ldclient-rb/impl/event_sender.rb
@@ -2,6 +2,8 @@
 
 require "securerandom"
 require "http"
+require "stringio"
+require "zlib"
 
 module LaunchDarkly
   module Impl
@@ -42,14 +44,17 @@ def send_event_data(event_data, description, is_diagnostic)
               @logger.debug { "[LDClient] sending #{description}: #{event_data}" }
               headers = {}
               headers["content-type"] = "application/json"
+              headers["content-encoding"] = "gzip"
               Impl::Util.default_http_headers(@sdk_key, @config).each { |k, v| headers[k] = v }
               unless is_diagnostic
                 headers["X-LaunchDarkly-Event-Schema"] = CURRENT_SCHEMA_VERSION.to_s
                 headers["X-LaunchDarkly-Payload-ID"] = payload_id
               end
+              gzip = Zlib::GzipWriter.new(StringIO.new)
+              gzip << event_data
               response = http_client.request("POST", uri, {
                 headers: headers,
-                body: event_data,
+                body: gzip.close.string,
               })
             rescue StandardError => exn
               @logger.warn { "[LDClient] Error sending events: #{exn.inspect}." }
diff --git a/spec/http_util.rb b/spec/http_util.rb
index 447c775a..ffc318b0 100644
--- a/spec/http_util.rb
+++ b/spec/http_util.rb
@@ -1,6 +1,8 @@
 require "webrick"
 require "webrick/httpproxy"
 require "webrick/https"
+require "stringio"
+require "zlib"
 
 class StubHTTPServer
   attr_reader :requests, :port
@@ -73,14 +75,13 @@ def record_request(req, res)
     @requests_queue << [req, req.body]
   end
 
-  def await_request
-    r = @requests_queue.pop
-    r[0]
-  end
-
   def await_request_with_body
     r = @requests_queue.pop
-    [r[0], r[1]]
+    body = r[1]
+
+    gz = Zlib::GzipReader.new(StringIO.new(body.to_s))
+
+    [r[0], gz.read]
   end
 end
 
diff --git a/spec/impl/event_sender_spec.rb b/spec/impl/event_sender_spec.rb
index c79855bc..dd48fcb4 100644
--- a/spec/impl/event_sender_spec.rb
+++ b/spec/impl/event_sender_spec.rb
@@ -37,8 +37,8 @@ def with_sender_and_server
           expect(result.must_shutdown).to be false
           expect(result.time_from_server).not_to be_nil
 
-          req = server.await_request
-          expect(req.body).to eq fake_data
+          req, body = server.await_request_with_body
+          expect(body).to eq fake_data
           expect(req.header).to include({
             "authorization" => [ sdk_key ],
             "content-type" => [ "application/json" ],
@@ -63,8 +63,8 @@ def with_sender_and_server
           result = es.send_event_data(fake_data, "", false)
 
           expect(result.success).to be true
-          req = server.await_request
-          expect(req.body).to eq fake_data
+          req, body = server.await_request_with_body
+          expect(body).to eq fake_data
           expect(req.host).to eq "fake-event-server"
         end
       end