diff --git a/tensorflow_probability/python/experimental/BUILD b/tensorflow_probability/python/experimental/BUILD
index f955ce118a..6ae164fef5 100644
--- a/tensorflow_probability/python/experimental/BUILD
+++ b/tensorflow_probability/python/experimental/BUILD
@@ -41,6 +41,7 @@ multi_substrate_py_library(
         "//tensorflow_probability/python/experimental/auto_batching",
         "//tensorflow_probability/python/experimental/marginalize",
         "//tensorflow_probability/python/experimental/nn",
+        "//tensorflow_probability/python/experimental/substrates",
         "//tensorflow_probability/python/experimental/timeseries",
         "//tensorflow_probability/python/internal:auto_composite_tensor",
         "//tensorflow_probability/python/experimental/util:composite_tensor",
@@ -63,6 +64,7 @@ multi_substrate_py_library(
         "//tensorflow_probability/python/experimental/sequential",
         "//tensorflow_probability/python/experimental/stats",
         "//tensorflow_probability/python/experimental/sts_gibbs",
+        "//tensorflow_probability/python/experimental/substrates",
         "//tensorflow_probability/python/experimental/tangent_spaces",
         "//tensorflow_probability/python/experimental/timeseries",
         "//tensorflow_probability/python/experimental/util",
diff --git a/tensorflow_probability/python/experimental/__init__.py b/tensorflow_probability/python/experimental/__init__.py
index d316a44d90..58a72d64ae 100644
--- a/tensorflow_probability/python/experimental/__init__.py
+++ b/tensorflow_probability/python/experimental/__init__.py
@@ -43,6 +43,7 @@
 from tensorflow_probability.python.experimental import sequential
 from tensorflow_probability.python.experimental import stats
 from tensorflow_probability.python.experimental import sts_gibbs
+from tensorflow_probability.python.experimental import substrates
 from tensorflow_probability.python.experimental import tangent_spaces
 from tensorflow_probability.python.experimental import timeseries
 from tensorflow_probability.python.experimental import util
@@ -75,6 +76,7 @@
     'sequential',
     'sts_gibbs',
     'stats',
+    'substrates',
     'tangent_spaces',
     'timeseries',
     'unnest',
diff --git a/tensorflow_probability/python/experimental/substrates/BUILD b/tensorflow_probability/python/experimental/substrates/BUILD
new file mode 100644
index 0000000000..c7f3bd836d
--- /dev/null
+++ b/tensorflow_probability/python/experimental/substrates/BUILD
@@ -0,0 +1,37 @@
+# Copyright 2019 The TensorFlow Probability Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ============================================================================
+# Description:
+#   API-unstable code that is part of the TFP package.
+
+# Placeholder: py_library
+
+package(
+    # default_applicable_licenses
+    default_visibility = [
+        "//tensorflow_probability:__subpackages__",
+    ],
+)
+
+licenses(["notice"])
+
+py_library(
+    name = "substrates",
+    srcs = ["__init__.py"],
+    deps = [
+        "//tensorflow_probability/python/internal:all_util",
+        "//tensorflow_probability/python/internal:lazy_loader",
+        "//tensorflow_probability/substrates",
+    ],
+)
diff --git a/tensorflow_probability/python/experimental/substrates/__init__.py b/tensorflow_probability/python/experimental/substrates/__init__.py
new file mode 100644
index 0000000000..6cc75af087
--- /dev/null
+++ b/tensorflow_probability/python/experimental/substrates/__init__.py
@@ -0,0 +1,33 @@
+# Copyright 2019 The TensorFlow Probability Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ============================================================================
+"""TensorFlow Probability alternative substrates."""
+
+from tensorflow_probability.python.internal import all_util
+from tensorflow_probability.python.internal import lazy_loader
+
+jax = lazy_loader.LazyLoader(
+    'jax', globals(),
+    'tensorflow_probability.substrates.jax')
+numpy = lazy_loader.LazyLoader(
+    'numpy', globals(),
+    'tensorflow_probability.substrates.numpy')
+
+
+_allowed_symbols = [
+    'jax',
+    'numpy',
+]
+
+all_util.remove_undocumented(__name__, _allowed_symbols)