diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index e29acc28dd8ad4a14b12277f92028138663c3dd5_Q0hBTkdFTE9HLnJzdA==..7d831f607206301265a1cb7d3e73cd1a087c985d_Q0hBTkdFTE9HLnJzdA== 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,13 @@
 Changelog
 =========
 
+.. _v3-1:
+
+3.1 - `master`_
+~~~~~~~~~~~~~~~
+
+.. note:: This version is not yet released and is under active development.
+
 .. _v3-0:
 
 3.0 - 2020-07-20
diff --git a/src/cryptography/__about__.py b/src/cryptography/__about__.py
index e29acc28dd8ad4a14b12277f92028138663c3dd5_c3JjL2NyeXB0b2dyYXBoeS9fX2Fib3V0X18ucHk=..7d831f607206301265a1cb7d3e73cd1a087c985d_c3JjL2NyeXB0b2dyYXBoeS9fX2Fib3V0X18ucHk= 100644
--- a/src/cryptography/__about__.py
+++ b/src/cryptography/__about__.py
@@ -22,7 +22,7 @@
 )
 __uri__ = "https://github.com/pyca/cryptography"
 
-__version__ = "3.0"
+__version__ = "3.1.dev1"
 
 __author__ = "The cryptography developers"
 __email__ = "cryptography-dev@python.org"
diff --git a/vectors/cryptography_vectors/__about__.py b/vectors/cryptography_vectors/__about__.py
index e29acc28dd8ad4a14b12277f92028138663c3dd5_dmVjdG9ycy9jcnlwdG9ncmFwaHlfdmVjdG9ycy9fX2Fib3V0X18ucHk=..7d831f607206301265a1cb7d3e73cd1a087c985d_dmVjdG9ycy9jcnlwdG9ncmFwaHlfdmVjdG9ycy9fX2Fib3V0X18ucHk= 100644
--- a/vectors/cryptography_vectors/__about__.py
+++ b/vectors/cryptography_vectors/__about__.py
@@ -20,7 +20,7 @@
 
 __uri__ = "https://github.com/pyca/cryptography"
 
-__version__ = "3.0"
+__version__ = "3.1.dev1"
 
 __author__ = "The cryptography developers"
 __email__ = "cryptography-dev@python.org"