diff --git a/BUILD b/BUILD
index ec8bed94f53..421d47fc4eb 100644
--- a/BUILD
+++ b/BUILD
@@ -227,11 +227,11 @@ config_setting(
 python_config_settings()
 
 # This should be updated along with build_handwritten.yaml
-g_stands_for = "gnarly"  # @unused
+g_stands_for = "gladiator"  # @unused
 
 core_version = "42.0.0"  # @unused
 
-version = "1.65.0-dev"  # @unused
+version = "1.66.0-dev"  # @unused
 
 GPR_PUBLIC_HDRS = [
     "include/grpc/support/alloc.h",
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c379a81ef28..05f7b1b58d1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,11 +25,11 @@
 cmake_minimum_required(VERSION 3.13)
 
 set(PACKAGE_NAME          "grpc")
-set(PACKAGE_VERSION       "1.65.0-dev")
+set(PACKAGE_VERSION       "1.66.0-dev")
 set(gRPC_CORE_VERSION     "42.0.0")
 set(gRPC_CORE_SOVERSION   "42")
-set(gRPC_CPP_VERSION      "1.65.0-dev")
-set(gRPC_CPP_SOVERSION    "1.65")
+set(gRPC_CPP_VERSION      "1.66.0-dev")
+set(gRPC_CPP_SOVERSION    "1.66")
 set(PACKAGE_STRING        "${PACKAGE_NAME} ${PACKAGE_VERSION}")
 set(PACKAGE_TARNAME       "${PACKAGE_NAME}-${PACKAGE_VERSION}")
 set(PACKAGE_BUGREPORT     "https://github.com/grpc/grpc/issues/")
diff --git a/Makefile b/Makefile
index 1d39b0f27e9..65243eda230 100644
--- a/Makefile
+++ b/Makefile
@@ -368,7 +368,7 @@ Q = @
 endif
 
 CORE_VERSION = 42.0.0
-CPP_VERSION = 1.65.0-dev
+CPP_VERSION = 1.66.0-dev
 
 CPPFLAGS_NO_ARCH += $(addprefix -I, $(INCLUDES)) $(addprefix -D, $(DEFINES))
 CPPFLAGS += $(CPPFLAGS_NO_ARCH) $(ARCH_FLAGS)
diff --git a/_metadata.py b/_metadata.py
index 448129f21db..f7fa656248d 100644
--- a/_metadata.py
+++ b/_metadata.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/_metadata.py.template`!!!
 
-__version__ = """1.65.0.dev0"""
+__version__ = """1.66.0.dev0"""
diff --git a/build_handwritten.yaml b/build_handwritten.yaml
index 33d07a997bf..a962dae84f8 100644
--- a/build_handwritten.yaml
+++ b/build_handwritten.yaml
@@ -14,9 +14,9 @@ settings:
   '#10': See the expand_version.py for all the quirks here
   core_version: 42.0.0
   csharp_major_version: 2
-  g_stands_for: gnarly
+  g_stands_for: gladiator
   protobuf_version: 3.26.1
-  version: 1.65.0-dev
+  version: 1.66.0-dev
 configs:
   asan:
     CC: clang
diff --git a/config.m4 b/config.m4
index 7a6ce84d3d7..656a4c92dcb 100644
--- a/config.m4
+++ b/config.m4
@@ -1381,7 +1381,7 @@ if test "$PHP_GRPC" != "no"; then
     -D_HAS_EXCEPTIONS=0 -DNOMINMAX -DGRPC_ARES=0 \
     -DGRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK=1 \
     -DGRPC_XDS_USER_AGENT_NAME_SUFFIX='"\"PHP\""' \
-    -DGRPC_XDS_USER_AGENT_VERSION_SUFFIX='"\"1.65.0dev\""')
+    -DGRPC_XDS_USER_AGENT_VERSION_SUFFIX='"\"1.66.0dev\""')
 
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/channelz)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/client_channel)
diff --git a/doc/g_stands_for.md b/doc/g_stands_for.md
index 2557a2f352e..035601582a7 100644
--- a/doc/g_stands_for.md
+++ b/doc/g_stands_for.md
@@ -64,4 +64,5 @@
 - 1.62 'g' stands for ['guardian'](https://github.com/grpc/grpc/tree/v1.62.x)
 - 1.63 'g' stands for ['giggle'](https://github.com/grpc/grpc/tree/v1.63.x)
 - 1.64 'g' stands for ['grateful'](https://github.com/grpc/grpc/tree/v1.64.x)
-- 1.65 'g' stands for ['gnarly'](https://github.com/grpc/grpc/tree/master)
+- 1.65 'g' stands for ['gnarly'](https://github.com/grpc/grpc/tree/v1.65.x)
+- 1.66 'g' stands for ['gladiator'](https://github.com/grpc/grpc/tree/master)
diff --git a/gRPC-C++.podspec b/gRPC-C++.podspec
index dcbb22b52a1..3d1bf649c3b 100644
--- a/gRPC-C++.podspec
+++ b/gRPC-C++.podspec
@@ -22,7 +22,7 @@
 Pod::Spec.new do |s|
   s.name     = 'gRPC-C++'
   # TODO (mxyan): use version that match gRPC version when pod is stabilized
-  version = '1.65.0-dev'
+  version = '1.66.0-dev'
   s.version  = version
   s.summary  = 'gRPC C++ library'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 1116516edbd..7570b10ea79 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-Core'
-  version = '1.65.0-dev'
+  version = '1.66.0-dev'
   s.version  = version
   s.summary  = 'Core cross-platform gRPC library, written in C'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-ProtoRPC.podspec b/gRPC-ProtoRPC.podspec
index 1e9bab7d451..faa604d2288 100644
--- a/gRPC-ProtoRPC.podspec
+++ b/gRPC-ProtoRPC.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-ProtoRPC'
-  version = '1.65.0-dev'
+  version = '1.66.0-dev'
   s.version  = version
   s.summary  = 'RPC library for Protocol Buffers, based on gRPC'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-RxLibrary.podspec b/gRPC-RxLibrary.podspec
index b1dd23fd87b..da292b55b37 100644
--- a/gRPC-RxLibrary.podspec
+++ b/gRPC-RxLibrary.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-RxLibrary'
-  version = '1.65.0-dev'
+  version = '1.66.0-dev'
   s.version  = version
   s.summary  = 'Reactive Extensions library for iOS/OSX.'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC.podspec b/gRPC.podspec
index b016e73b775..9fb3fc6158d 100644
--- a/gRPC.podspec
+++ b/gRPC.podspec
@@ -20,7 +20,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC'
-  version = '1.65.0-dev'
+  version = '1.66.0-dev'
   s.version  = version
   s.summary  = 'gRPC client library for iOS/OSX'
   s.homepage = 'https://grpc.io'
diff --git a/include/grpcpp/version_info.h b/include/grpcpp/version_info.h
index 0860a237de6..dfab77a3020 100644
--- a/include/grpcpp/version_info.h
+++ b/include/grpcpp/version_info.h
@@ -19,9 +19,9 @@
 #define GRPCPP_VERSION_INFO_H
 
 #define GRPC_CPP_VERSION_MAJOR 1
-#define GRPC_CPP_VERSION_MINOR 65
+#define GRPC_CPP_VERSION_MINOR 66
 #define GRPC_CPP_VERSION_PATCH 0
 #define GRPC_CPP_VERSION_TAG "dev"
-#define GRPC_CPP_VERSION_STRING "1.65.0-dev"
+#define GRPC_CPP_VERSION_STRING "1.66.0-dev"
 
 #endif  // GRPCPP_VERSION_INFO_H
diff --git a/package.xml b/package.xml
index 523bc3aa67b..404152ed385 100644
--- a/package.xml
+++ b/package.xml
@@ -13,8 +13,8 @@
  <date>2019-09-24</date>
  <time>16:06:07</time>
  <version>
-  <release>1.65.0dev</release>
-  <api>1.65.0dev</api>
+  <release>1.66.0dev</release>
+  <api>1.66.0dev</api>
  </version>
  <stability>
   <release>beta</release>
@@ -22,7 +22,7 @@
  </stability>
  <license>Apache 2.0</license>
  <notes>
-- gRPC Core 1.65.0 update
+- gRPC Core 1.66.0 update
  </notes>
  <contents>
   <dir baseinstalldir="/" name="/">
diff --git a/src/core/lib/surface/version.cc b/src/core/lib/surface/version.cc
index 000fa58b982..a24a26ba4bf 100644
--- a/src/core/lib/surface/version.cc
+++ b/src/core/lib/surface/version.cc
@@ -24,4 +24,4 @@
 
 const char* grpc_version_string(void) { return "42.0.0"; }
 
-const char* grpc_g_stands_for(void) { return "gnarly"; }
+const char* grpc_g_stands_for(void) { return "gladiator"; }
diff --git a/src/csharp/build/dependencies.props b/src/csharp/build/dependencies.props
index 283650bf0bf..50580b4379d 100644
--- a/src/csharp/build/dependencies.props
+++ b/src/csharp/build/dependencies.props
@@ -1,7 +1,7 @@
 <!-- This file is generated -->
 <Project>
   <PropertyGroup>
-    <GrpcCsharpVersion>2.65.0-dev</GrpcCsharpVersion>
+    <GrpcCsharpVersion>2.66.0-dev</GrpcCsharpVersion>
     <GoogleProtobufVersion>3.26.1</GoogleProtobufVersion>
   </PropertyGroup>
 </Project>
diff --git a/src/objective-c/!ProtoCompiler-gRPCCppPlugin.podspec b/src/objective-c/!ProtoCompiler-gRPCCppPlugin.podspec
index e05420911b5..13c4feb9851 100644
--- a/src/objective-c/!ProtoCompiler-gRPCCppPlugin.podspec
+++ b/src/objective-c/!ProtoCompiler-gRPCCppPlugin.podspec
@@ -42,7 +42,7 @@ Pod::Spec.new do |s|
   # exclamation mark ensures that other "regular" pods will be able to find it as it'll be installed
   # before them.
   s.name     = '!ProtoCompiler-gRPCCppPlugin'
-  v = '1.65.0-dev'
+  v = '1.66.0-dev'
   s.version  = v
   s.summary  = 'The gRPC ProtoC plugin generates C++ files from .proto services.'
   s.description = <<-DESC
diff --git a/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec b/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
index 10255961d05..50393388a65 100644
--- a/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
+++ b/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
@@ -42,7 +42,7 @@ Pod::Spec.new do |s|
   # exclamation mark ensures that other "regular" pods will be able to find it as it'll be installed
   # before them.
   s.name     = '!ProtoCompiler-gRPCPlugin'
-  v = '1.65.0-dev'
+  v = '1.66.0-dev'
   s.version  = v
   s.summary  = 'The gRPC ProtoC plugin generates Objective-C files from .proto services.'
   s.description = <<-DESC
diff --git a/src/objective-c/GRPCClient/version.h b/src/objective-c/GRPCClient/version.h
index c3e2f050573..0eb2c9b5623 100644
--- a/src/objective-c/GRPCClient/version.h
+++ b/src/objective-c/GRPCClient/version.h
@@ -22,4 +22,4 @@
 // instead. This file can be regenerated from the template by running
 // `tools/buildgen/generate_projects.sh`.
 
-#define GRPC_OBJC_VERSION_STRING @"1.65.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.66.0-dev"
diff --git a/src/objective-c/tests/version.h b/src/objective-c/tests/version.h
index 8c4b54f4b9b..b79755fb413 100644
--- a/src/objective-c/tests/version.h
+++ b/src/objective-c/tests/version.h
@@ -22,5 +22,5 @@
 // instead. This file can be regenerated from the template by running
 // `tools/buildgen/generate_projects.sh`.
 
-#define GRPC_OBJC_VERSION_STRING @"1.65.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.66.0-dev"
 #define GRPC_C_VERSION_STRING @"42.0.0"
diff --git a/src/php/composer.json b/src/php/composer.json
index fc2d89bacc6..4a2e463446d 100644
--- a/src/php/composer.json
+++ b/src/php/composer.json
@@ -2,7 +2,7 @@
   "name": "grpc/grpc-dev",
   "description": "gRPC library for PHP - for Development use only",
   "license": "Apache-2.0",
-  "version": "1.65.0",
+  "version": "1.66.0",
   "require": {
     "php": ">=7.0.0",
     "google/protobuf": "^v3.3.0"
diff --git a/src/php/ext/grpc/version.h b/src/php/ext/grpc/version.h
index 1198590fce8..d6707d14dd9 100644
--- a/src/php/ext/grpc/version.h
+++ b/src/php/ext/grpc/version.h
@@ -20,6 +20,6 @@
 #ifndef VERSION_H
 #define VERSION_H
 
-#define PHP_GRPC_VERSION "1.65.0dev"
+#define PHP_GRPC_VERSION "1.66.0dev"
 
 #endif /* VERSION_H */
diff --git a/src/python/grpcio/grpc/_grpcio_metadata.py b/src/python/grpcio/grpc/_grpcio_metadata.py
index 76c35c1f7e8..346dc174f61 100644
--- a/src/python/grpcio/grpc/_grpcio_metadata.py
+++ b/src/python/grpcio/grpc/_grpcio_metadata.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc/_grpcio_metadata.py.template`!!!
 
-__version__ = """1.65.0.dev0"""
+__version__ = """1.66.0.dev0"""
diff --git a/src/python/grpcio/grpc_version.py b/src/python/grpcio/grpc_version.py
index 04a5cfab351..50f7b58af28 100644
--- a/src/python/grpcio/grpc_version.py
+++ b/src/python/grpcio/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_admin/grpc_version.py b/src/python/grpcio_admin/grpc_version.py
index 56ee7509fe3..b0944e4e43f 100644
--- a/src/python/grpcio_admin/grpc_version.py
+++ b/src/python/grpcio_admin/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_admin/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_channelz/grpc_version.py b/src/python/grpcio_channelz/grpc_version.py
index 86365f4999b..e3293182f32 100644
--- a/src/python/grpcio_channelz/grpc_version.py
+++ b/src/python/grpcio_channelz/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_channelz/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_csds/grpc_version.py b/src/python/grpcio_csds/grpc_version.py
index 18065fb541f..8f0a7e79124 100644
--- a/src/python/grpcio_csds/grpc_version.py
+++ b/src/python/grpcio_csds/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_csds/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_csm_observability/grpc_version.py b/src/python/grpcio_csm_observability/grpc_version.py
index 930d11a6dcb..cce1b57a924 100644
--- a/src/python/grpcio_csm_observability/grpc_version.py
+++ b/src/python/grpcio_csm_observability/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_csm_observability/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_health_checking/grpc_version.py b/src/python/grpcio_health_checking/grpc_version.py
index c7ba0bb48c0..6a0fa81e984 100644
--- a/src/python/grpcio_health_checking/grpc_version.py
+++ b/src/python/grpcio_health_checking/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_health_checking/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_observability/grpc_version.py b/src/python/grpcio_observability/grpc_version.py
index fe35dea3396..13cab2cde35 100644
--- a/src/python/grpcio_observability/grpc_version.py
+++ b/src/python/grpcio_observability/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_observability/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_reflection/grpc_version.py b/src/python/grpcio_reflection/grpc_version.py
index 87faf2e5b6c..d4f5d1d484a 100644
--- a/src/python/grpcio_reflection/grpc_version.py
+++ b/src/python/grpcio_reflection/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_reflection/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_status/grpc_version.py b/src/python/grpcio_status/grpc_version.py
index 81683b8dcbe..b1e73450284 100644
--- a/src/python/grpcio_status/grpc_version.py
+++ b/src/python/grpcio_status/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_status/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_testing/grpc_version.py b/src/python/grpcio_testing/grpc_version.py
index f8f21a864b2..34303c2934f 100644
--- a/src/python/grpcio_testing/grpc_version.py
+++ b/src/python/grpcio_testing/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_testing/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/python/grpcio_tests/grpc_version.py b/src/python/grpcio_tests/grpc_version.py
index 0e4f3b44a1d..85effbb7a8c 100644
--- a/src/python/grpcio_tests/grpc_version.py
+++ b/src/python/grpcio_tests/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_tests/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/src/ruby/lib/grpc/version.rb b/src/ruby/lib/grpc/version.rb
index 73860d15afb..b44360856f2 100644
--- a/src/ruby/lib/grpc/version.rb
+++ b/src/ruby/lib/grpc/version.rb
@@ -14,5 +14,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '1.65.0.dev'
+  VERSION = '1.66.0.dev'
 end
diff --git a/src/ruby/nativedebug/version.rb b/src/ruby/nativedebug/version.rb
index a82d2ce2788..73bd2ba09c2 100644
--- a/src/ruby/nativedebug/version.rb
+++ b/src/ruby/nativedebug/version.rb
@@ -14,6 +14,6 @@
 
 module GRPC
   module NativeDebug
-    VERSION = '1.65.0.dev'
+    VERSION = '1.66.0.dev'
   end
 end
diff --git a/src/ruby/tools/version.rb b/src/ruby/tools/version.rb
index 3d5fddb60d1..5768776a546 100644
--- a/src/ruby/tools/version.rb
+++ b/src/ruby/tools/version.rb
@@ -14,6 +14,6 @@
 
 module GRPC
   module Tools
-    VERSION = '1.65.0.dev'
+    VERSION = '1.66.0.dev'
   end
 end
diff --git a/tools/distrib/python/grpc_version.py b/tools/distrib/python/grpc_version.py
index 867c46e3c86..64b598204bb 100644
--- a/tools/distrib/python/grpc_version.py
+++ b/tools/distrib/python/grpc_version.py
@@ -14,5 +14,5 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/tools/distrib/python/grpcio_tools/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
 PROTOBUF_VERSION = '3.26.1'
diff --git a/tools/distrib/python/grpcio_tools/grpc_tools/grpc_version.py b/tools/distrib/python/grpcio_tools/grpc_tools/grpc_version.py
index 7f98c77d05c..faa89ddf837 100644
--- a/tools/distrib/python/grpcio_tools/grpc_tools/grpc_version.py
+++ b/tools/distrib/python/grpcio_tools/grpc_tools/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/tools/distrib/python/grpcio_tools/grpc_tools/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
diff --git a/tools/distrib/python/grpcio_tools/grpc_version.py b/tools/distrib/python/grpcio_tools/grpc_version.py
index e343f013c38..b39fde76487 100644
--- a/tools/distrib/python/grpcio_tools/grpc_version.py
+++ b/tools/distrib/python/grpcio_tools/grpc_version.py
@@ -14,5 +14,5 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/tools/distrib/python/grpcio_tools/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
 PROTOBUF_VERSION = '3.26.1'
diff --git a/tools/distrib/python/xds_protos/grpc_version.py b/tools/distrib/python/xds_protos/grpc_version.py
index 6c029a2f261..d5fa6b588f6 100644
--- a/tools/distrib/python/xds_protos/grpc_version.py
+++ b/tools/distrib/python/xds_protos/grpc_version.py
@@ -14,5 +14,5 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/tools/distrib/python/grpcio_tools/grpc_version.py.template`!!!
 
-VERSION = '1.65.0.dev0'
+VERSION = '1.66.0.dev0'
 PROTOBUF_VERSION = '3.26.1'
diff --git a/tools/doxygen/Doxyfile.c++ b/tools/doxygen/Doxyfile.c++
index 01b0f97652a..f57337eed8b 100644
--- a/tools/doxygen/Doxyfile.c++
+++ b/tools/doxygen/Doxyfile.c++
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC C++"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.65.0-dev
+PROJECT_NUMBER         = 1.66.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index 49d88672e31..e60ed913d9a 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC C++"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.65.0-dev
+PROJECT_NUMBER         = 1.66.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/tools/doxygen/Doxyfile.objc b/tools/doxygen/Doxyfile.objc
index b6d8167d0b8..02b3f3b6fff 100644
--- a/tools/doxygen/Doxyfile.objc
+++ b/tools/doxygen/Doxyfile.objc
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC Objective-C"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.65.0-dev
+PROJECT_NUMBER         = 1.66.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/tools/doxygen/Doxyfile.objc.internal b/tools/doxygen/Doxyfile.objc.internal
index 9d397ef0336..5b38b0690f4 100644
--- a/tools/doxygen/Doxyfile.objc.internal
+++ b/tools/doxygen/Doxyfile.objc.internal
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC Objective-C"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.65.0-dev
+PROJECT_NUMBER         = 1.66.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/tools/doxygen/Doxyfile.php b/tools/doxygen/Doxyfile.php
index ac527bd3115..c71e3d6d640 100644
--- a/tools/doxygen/Doxyfile.php
+++ b/tools/doxygen/Doxyfile.php
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC PHP"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.65.0-dev
+PROJECT_NUMBER         = 1.66.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a