diff --git a/pipenv/cli.py b/pipenv/cli.py
index 77a273b8..0566a6f7 100644
--- a/pipenv/cli.py
+++ b/pipenv/cli.py
@@ -24,7 +24,8 @@ from .utils import (convert_deps_from_pip, convert_deps_to_pip, is_required_vers
     proper_case, pep423_name, split_vcs)
 from .__version__ import __version__
 from . import pep508checker, progress
-from .environments import PIPENV_COLORBLIND, PIPENV_NOSPIN, PIPENV_SHELL_COMPAT, PIPENV_VENV_IN_PROJECT
+from .environments import PIPENV_COLORBLIND, PIPENV_NOSPIN, PIPENV_SHELL_COMPAT
+from .environments import PIPENV_DEFAULT_THREE, PIPENV_VENV_IN_PROJECT
 
 # Backport required for earlier versions of Python.
 if sys.version_info < (3, 3):
@@ -151,6 +152,11 @@ def ensure_virtualenv(three=None, python=None):
 
 def ensure_project(three=None, python=None, validate=True):
     """Ensures both Pipfile and virtualenv exist for the project."""
+
+    # Support for default three mode.
+    if PIPENV_DEFAULT_THREE:
+        three = True
+
     ensure_pipfile(validate=validate)
     ensure_virtualenv(three=three, python=python)
 
diff --git a/pipenv/environments.py b/pipenv/environments.py
index f4cd81aa..bac0d2f8 100644
--- a/pipenv/environments.py
+++ b/pipenv/environments.py
@@ -22,6 +22,9 @@ PIPENV_NOSPIN = os.environ.get('PIPENV_NOSPIN')
 # Note: +1 because of a temporary bug in Pipenv.
 PIPENV_MAX_DEPTH = int(os.environ.get('PIPENV_MAX_DEPTH', '3')) + 1
 
+# Tells Pipenv to use Python three by default.
+PIPENV_DEFAULT_THREE = os.environ.get('PIPENV_DEFAULT_THREE')
+
 # Use shell compatibility mode when using venv in project mode.
 if PIPENV_VENV_IN_PROJECT:
     PIPENV_SHELL_COMPAT = True