Flagging 0.13.1-pre1.
diff --git a/Makefile b/Makefile
index 5927d24..83a85c9 100644
--- a/Makefile
+++ b/Makefile
@@ -361,7 +361,7 @@
 Q = @
 endif
 
-VERSION = 0.13.0
+VERSION = 0.13.1-pre1
 
 CPPFLAGS_NO_ARCH += $(addprefix -I, $(INCLUDES)) $(addprefix -D, $(DEFINES))
 CPPFLAGS += $(CPPFLAGS_NO_ARCH) $(ARCH_FLAGS)
diff --git a/build.yaml b/build.yaml
index 598d313..ec208ee 100644
--- a/build.yaml
+++ b/build.yaml
@@ -7,7 +7,7 @@
   '#3': Use "-preN" suffixes to identify pre-release versions
   '#4': Per-language overrides are possible with (eg) ruby_version tag here
   '#5': See the expand_version.py for all the quirks here
-  version: 0.13.0
+  version: 0.13.1-pre1
 filegroups:
 - name: census
   public_headers:
diff --git a/package.json b/package.json
index 827231c..94e8d03 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "grpc",
-  "version": "0.13.0",
+  "version": "0.13.1-pre1",
   "author": "Google Inc.",
   "description": "gRPC Library for Node",
   "homepage": "http://www.grpc.io/",
diff --git a/src/core/surface/version.c b/src/core/surface/version.c
index c8de753..19f0983 100644
--- a/src/core/surface/version.c
+++ b/src/core/surface/version.c
@@ -36,4 +36,4 @@
 
 #include <grpc/grpc.h>
 
-const char *grpc_version_string(void) { return "0.13.0"; }
+const char *grpc_version_string(void) { return "0.13.1-pre1"; }
diff --git a/src/csharp/Grpc.Core/VersionInfo.cs b/src/csharp/Grpc.Core/VersionInfo.cs
index d62cd4f..04741ae 100644
--- a/src/csharp/Grpc.Core/VersionInfo.cs
+++ b/src/csharp/Grpc.Core/VersionInfo.cs
@@ -41,11 +41,11 @@
         /// <summary>
         /// Current version of gRPC C# assemblies
         /// </summary>
-        public const string CurrentAssemblyVersion = "0.13.0.0";
+        public const string CurrentAssemblyVersion = "0.13.1.0";
 
         /// <summary>
         /// Current version of gRPC C#
         /// </summary>
-        public const string CurrentVersion = "0.13.0";
+        public const string CurrentVersion = "0.13.1-pre1";
     }
 }
diff --git a/src/csharp/build_packages.bat b/src/csharp/build_packages.bat
index e423545..7cf962b 100644
--- a/src/csharp/build_packages.bat
+++ b/src/csharp/build_packages.bat
@@ -1,7 +1,7 @@
 @rem Builds gRPC NuGet packages
 
 @rem Current package versions
-set VERSION=0.13.0
+set VERSION=0.13.1-pre1
 set PROTOBUF_VERSION=3.0.0-beta2
 
 @rem Packages that depend on prerelease packages (like Google.Protobuf) need to have prerelease suffix as well.
diff --git a/src/python/grpcio/grpc_version.py b/src/python/grpcio/grpc_version.py
index 45a1073..db23de2 100644
--- a/src/python/grpcio/grpc_version.py
+++ b/src/python/grpcio/grpc_version.py
@@ -29,4 +29,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc_version.py.template`!!!
 
-VERSION='0.13.0'
+VERSION='0.13.1rc1'
diff --git a/src/ruby/lib/grpc/version.rb b/src/ruby/lib/grpc/version.rb
index 95e1b82..42c94f0 100644
--- a/src/ruby/lib/grpc/version.rb
+++ b/src/ruby/lib/grpc/version.rb
@@ -29,5 +29,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '0.13.0'
+  VERSION = '0.13.1.pre1'
 end
diff --git a/tools/doxygen/Doxyfile.c++ b/tools/doxygen/Doxyfile.c++
index 1a62f0f..0123a4b 100644
--- a/tools/doxygen/Doxyfile.c++
+++ b/tools/doxygen/Doxyfile.c++
@@ -40,7 +40,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 0.13.0
+PROJECT_NUMBER         = 0.13.1-pre1
 
 # 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 84449e5..da50923 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -40,7 +40,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 0.13.0
+PROJECT_NUMBER         = 0.13.1-pre1
 
 # 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.core b/tools/doxygen/Doxyfile.core
index 3067683..8995cfb 100644
--- a/tools/doxygen/Doxyfile.core
+++ b/tools/doxygen/Doxyfile.core
@@ -40,7 +40,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 0.13.0
+PROJECT_NUMBER         = 0.13.1-pre1
 
 # 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.core.internal b/tools/doxygen/Doxyfile.core.internal
index a3e899f..fb6958f 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -40,7 +40,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 0.13.0
+PROJECT_NUMBER         = 0.13.1-pre1
 
 # 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