diff --git a/example_manifest.yaml b/example_manifest.yaml
new file mode 100644
index 00000000..426b8545
--- /dev/null
+++ b/example_manifest.yaml
@@ -0,0 +1,31 @@
+
+# Hooks are set up as follows
+# hooks:
+#     -
+#         id: hook_id
+#         name: 'Readable name'
+#         entry: my_hook_executable
+#
+#         # Optional
+#         description: 'Longer description of the hook'
+#
+#         # Optional, for now 'python[optional version]', 'ruby #.#.#', 'node'
+#         language: 'python'
+#
+#         # Optional, defaults to zero
+#         expected_return_value: 0
+
+hooks:
+    -
+        id: my_hook
+        name: My Simple Hook
+        description: This is my simple hook that does blah
+        entry: my-simple-hook.py
+        language: python
+        expected_return_value: 0
+    -
+        id: my_grep_based_hook
+        name: My Bash Based Hook
+        description: This is a hook that uses grep to validate some stuff
+        entry: ./my_grep_based_hook.sh
+        expected_return_value: 1
diff --git a/pre_commit/clientlib/__init__.py b/pre_commit/clientlib/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/pre_commit/clientlib/validate_manifest.py b/pre_commit/clientlib/validate_manifest.py
new file mode 100644
index 00000000..035114e3
--- /dev/null
+++ b/pre_commit/clientlib/validate_manifest.py
@@ -0,0 +1,97 @@
+
+from __future__ import print_function
+
+import argparse
+import jsonschema
+import jsonschema.exceptions
+import os.path
+import yaml
+
+import pre_commit.constants as C
+
+
+class InvalidManifestError(ValueError): pass
+
+
+MANIFEST_JSON_SCHEMA = {
+    'type': 'object',
+    'properties': {
+        'hooks': {
+            'type': 'array',
+            'minItems': 1,
+            'items': {
+                'type': 'object',
+                'properties': {
+                    'id': {'type': 'string'},
+                    'name': {'type': 'string'},
+                    'description': {'type': 'string'},
+                    'entry': {'type': 'string'},
+                    'language': {'type': 'string'},
+                    'expected_return_value': {'type': 'number'},
+                },
+                'required': ['id', 'name', 'entry'],
+            },
+        },
+    },
+    'required': ['hooks'],
+}
+
+
+def check_is_valid_manifest(file_contents):
+    file_objects = yaml.load(file_contents)
+
+    jsonschema.validate(file_objects, MANIFEST_JSON_SCHEMA)
+
+    for hook_config in file_objects['hooks']:
+        language = hook_config.get('language')
+
+        if language is not None and not any(
+            language.startswith(lang) for lang in C.SUPPORTED_LANGUAGES
+        ):
+            raise InvalidManifestError(
+                'Expected language {0} for {1} to start with one of {2!r}'.format(
+                    hook_config['id'],
+                    hook_config['language'],
+                    C.SUPPORTED_LANGUAGES,
+                )
+            )
+
+
+def run(argv):
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        '--filename',
+        required=False, default=None,
+        help='Manifest filename.  Defaults to {0} at root of git repo'.format(
+            C.MANIFEST_FILE,
+        )
+    )
+    args = parser.parse_args(argv)
+
+    if args.filename is None:
+        # TODO: filename = git.get_root() + C.MANIFEST_FILE
+        raise NotImplementedError
+    else:
+        filename = args.filename
+
+    if not os.path.exists(filename):
+        print('File {0} does not exist'.format(filename))
+        return 1
+
+    file_contents = open(filename, 'r').read()
+
+    try:
+        yaml.load(file_contents)
+    except Exception as e:
+        print('File {0} is not a valid yaml file'.format(filename))
+        print(str(e))
+        return 1
+
+    try:
+        check_is_valid_manifest(file_contents)
+    except (jsonschema.exceptions.ValidationError, InvalidManifestError) as e:
+        print('File {0} is not a valid manifest file'.format(filename))
+        print(str(e))
+        return 1
+
+    return 0
\ No newline at end of file
diff --git a/pre_commit/constants.py b/pre_commit/constants.py
new file mode 100644
index 00000000..ecf02bcf
--- /dev/null
+++ b/pre_commit/constants.py
@@ -0,0 +1,12 @@
+
+PRE_COMMIT_FILE = '.pre-commit-config.yaml'
+
+PRE_COMMIT_DIR = '.pre-commit-files'
+
+MANIFEST_FILE = 'manifest.yaml'
+
+SUPPORTED_LANGUAGES = [
+    'python',
+    'ruby',
+    'node',
+]
\ No newline at end of file
diff --git a/pre_commit/entry_points.py b/pre_commit/entry_points.py
new file mode 100644
index 00000000..4d508256
--- /dev/null
+++ b/pre_commit/entry_points.py
@@ -0,0 +1,23 @@
+
+import functools
+
+import pre_commit.clientlib.validate_manifest
+import pre_commit.run
+
+
+def make_entry_point(entry_point_func):
+    """Decorator which turns a function which takes sys.argv[1:] and returns
+    an integer into an argumentless function which returns an integer.
+
+    Args:
+        entry_point_func - A function which takes an array representing argv
+    """
+    @functools.wraps(entry_point_func)
+    def func():
+        import sys
+        return entry_point_func(sys.argv[1:])
+    return func
+
+
+pre_commit_func = make_entry_point(pre_commit.run.run)
+validate_manifest_func = make_entry_point(pre_commit.clientlib.validate_manifest.run)
\ No newline at end of file
diff --git a/pre_commit/run.py b/pre_commit/run.py
index 5fa1741d..400cbc9d 100644
--- a/pre_commit/run.py
+++ b/pre_commit/run.py
@@ -34,8 +34,8 @@ def run(argv):
     args = parser.parse_args(argv)
 
     if args.install:
-        install()
+        return install()
     elif args.uninstall:
-        uninstall()
+        return uninstall()
     else:
-        run_hooks(args)
\ No newline at end of file
+        return run_hooks(args)
diff --git a/requirements.txt b/requirements.txt
index 3e103960..ccb06e82 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
 argparse
+jsonschema
 plumbum
 pyyaml
 simplejson
diff --git a/setup.py b/setup.py
index 1f456312..449342ce 100644
--- a/setup.py
+++ b/setup.py
@@ -12,7 +12,15 @@ setup(
     },
     install_requires=[
         'argparse',
+        'jsonschema',
         'plumbum',
+        'pyyaml',
         'simplejson',
     ],
+    entry_points={
+        'console_scripts': [
+            'pre-commit = pre_commit.entry_points:pre_commit_func',
+            'validate-manifest = pre_commit.entry_points:validate_manifest_func',
+        ],
+    }
 )
diff --git a/tests/clientlib/__init__.py b/tests/clientlib/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/clientlib/validate_manifest_test.py b/tests/clientlib/validate_manifest_test.py
new file mode 100644
index 00000000..7996525d
--- /dev/null
+++ b/tests/clientlib/validate_manifest_test.py
@@ -0,0 +1,86 @@
+
+import __builtin__
+import jsonschema
+import pytest
+import mock
+
+from pre_commit.clientlib.validate_manifest import check_is_valid_manifest
+from pre_commit.clientlib.validate_manifest import InvalidManifestError
+from pre_commit.clientlib.validate_manifest import run
+
+
+@pytest.yield_fixture
+def print_mock():
+    with mock.patch.object(__builtin__, 'print', autospec=True) as print_mock_obj:
+        yield print_mock_obj
+
+
+def test_run_returns_1_for_non_existent_module(print_mock):
+    non_existent_filename = 'file_that_does_not_exist'
+    ret = run(['--filename', non_existent_filename])
+    assert ret == 1
+    print_mock.assert_called_once_with(
+        'File {0} does not exist'.format(non_existent_filename),
+    )
+
+
+def test_run_returns_1_for_non_yaml_file(print_mock):
+    non_parseable_filename = 'tests/data/non_parseable_yaml_file.yaml'
+    ret = run(['--filename', non_parseable_filename])
+    assert ret == 1
+    print_mock.assert_any_call(
+        'File {0} is not a valid yaml file'.format(non_parseable_filename),
+    )
+
+
+def test_returns_1_for_valid_yaml_file_but_invalid_manifest(print_mock):
+    invalid_manifest = 'tests/data/valid_yaml_but_invalid_manifest.yaml'
+    ret = run(['--filename', invalid_manifest])
+    assert ret == 1
+    print_mock.assert_any_call(
+        'File {0} is not a valid manifest file'.format(invalid_manifest)
+    )
+
+
+def test_returns_0_for_valid_manifest():
+    valid_manifest = 'example_manifest.yaml'
+    ret = run(['--filename', valid_manifest])
+    assert ret == 0
+
+
+@pytest.mark.parametrize(('manifest', 'expected_exception_type'), (
+    (
+        """
+hooks:
+    -
+        id: foo
+        entry: foo
+        """,
+        jsonschema.exceptions.ValidationError,
+    ),
+    (
+        """
+hooks:
+    -
+        id: foo
+        name: Foo
+        language: Not a Language lol
+        entry: foo
+        """,
+        InvalidManifestError,
+    ),
+))
+def test_check_invalid_manifests(manifest, expected_exception_type):
+    with pytest.raises(expected_exception_type):
+        check_is_valid_manifest(manifest)
+
+
+def test_valid_manifest_is_valid():
+    check_is_valid_manifest("""
+hooks:
+    -
+        id: foo
+        name: Foo
+        entry: foo
+        language: python>2.6
+    """)
diff --git a/tests/data/non_parseable_yaml_file.yaml b/tests/data/non_parseable_yaml_file.yaml
new file mode 100644
index 00000000..cdadb58f
--- /dev/null
+++ b/tests/data/non_parseable_yaml_file.yaml
@@ -0,0 +1 @@
+foo: "
\ No newline at end of file
diff --git a/tests/data/valid_yaml_but_invalid_manifest.yaml b/tests/data/valid_yaml_but_invalid_manifest.yaml
new file mode 100644
index 00000000..7daacd5d
--- /dev/null
+++ b/tests/data/valid_yaml_but_invalid_manifest.yaml
@@ -0,0 +1 @@
+foo: bar
\ No newline at end of file