diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 3f327c0..260e5cb 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -1577,7 +1577,7 @@
      stored; by default ``None`` and no value is stored
 
    * required_ - Whether or not a subcommand must be provided, by default
-     ``True``.
+     ``False``.
 
    * help_ - help for sub-parser group in help output, by default ``None``
 
diff --git a/Lib/argparse.py b/Lib/argparse.py
index e3da7f0..e0e367b 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1077,7 +1077,7 @@
                  prog,
                  parser_class,
                  dest=SUPPRESS,
-                 required=True,
+                 required=False,
                  help=None,
                  metavar=None):
 
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index c4440e4..bcf15ce 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1932,7 +1932,9 @@
         parser = ErrorRaisingArgumentParser()
         subparsers = parser.add_subparsers(dest='command')
         subparsers.add_parser('run')
-        self._test_required_subparsers(parser)
+        # No error here
+        ret = parser.parse_args(())
+        self.assertIsNone(ret.command)
 
     def test_optional_subparsers(self):
         parser = ErrorRaisingArgumentParser()
diff --git a/Misc/NEWS.d/3.7.0a2.rst b/Misc/NEWS.d/3.7.0a2.rst
index 190038d..621de6d 100644
--- a/Misc/NEWS.d/3.7.0a2.rst
+++ b/Misc/NEWS.d/3.7.0a2.rst
@@ -477,6 +477,8 @@
 argparse subparsers are now required by default.  This matches behaviour in
 Python 2. For optional subparsers, use the new parameter
 ``add_subparsers(required=False)``. Patch by Anthony Sottile.
+(As of 3.7.0rc1, the default was changed to not required as had been the case
+since Python 3.3.)
 
 ..
 
diff --git a/Misc/NEWS.d/next/Library/2018-05-16-14-57-58.bpo-33109.nPLL_S.rst b/Misc/NEWS.d/next/Library/2018-05-16-14-57-58.bpo-33109.nPLL_S.rst
new file mode 100644
index 0000000..be731f9
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-05-16-14-57-58.bpo-33109.nPLL_S.rst
@@ -0,0 +1,2 @@
+argparse subparsers are once again not required by default, reverting the
+change in behavior introduced by bpo-26510 in 3.7.0a2.