diff --git a/optimizely/event/__init__.py b/optimizely/event/__init__.py
new file mode 100644
index 00000000..d6094e5a
--- /dev/null
+++ b/optimizely/event/__init__.py
@@ -0,0 +1,12 @@
+# Copyright 2019, Optimizely
+# 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.
diff --git a/optimizely/event/entity/__init__.py b/optimizely/event/entity/__init__.py
new file mode 100644
index 00000000..d6094e5a
--- /dev/null
+++ b/optimizely/event/entity/__init__.py
@@ -0,0 +1,12 @@
+# Copyright 2019, Optimizely
+# 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.
diff --git a/optimizely/event/entity/conversion_event.py b/optimizely/event/entity/conversion_event.py
new file mode 100644
index 00000000..e6cd746d
--- /dev/null
+++ b/optimizely/event/entity/conversion_event.py
@@ -0,0 +1,25 @@
+# Copyright 2019 Optimizely
+# 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.
+from .user_event import UserEvent
+
+
+class ConversionEvent(UserEvent):
+  """ Class representing Conversion Event. """
+
+  def __init__(self, event_context, event, user_id, visitor_attributes, event_tags, bot_filtering=None):
+    self.event_context = event_context
+    self.event = event
+    self.user_id = user_id
+    self.visitor_attributes = visitor_attributes
+    self.event_tags = event_tags
+    self.bot_filtering = bot_filtering
diff --git a/optimizely/event/entity/decision.py b/optimizely/event/entity/decision.py
new file mode 100644
index 00000000..60b965dc
--- /dev/null
+++ b/optimizely/event/entity/decision.py
@@ -0,0 +1,19 @@
+# Copyright 2019 Optimizely
+# 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.
+
+
+class Decision(object):
+  def __init__(self, compaign_id, experiment_id, variation_id):
+    self.campaign_id = compaign_id
+    self.experiment_id = experiment_id
+    self.variation_id = variation_id
diff --git a/optimizely/event/entity/event_batch.py b/optimizely/event/entity/event_batch.py
new file mode 100644
index 00000000..4bdf008c
--- /dev/null
+++ b/optimizely/event/entity/event_batch.py
@@ -0,0 +1,25 @@
+# Copyright 2019 Optimizely
+# 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.
+
+
+class EventBatch(object):
+  def __init__(self, account_id, project_id, revision, client_name, client_version,
+               anonymize_ip, enrich_decisions, visitors=None):
+    self.account_id = account_id
+    self.project_id = project_id
+    self.revision = revision
+    self.client_name = client_name
+    self.client_version = client_version
+    self.anonymize_ip = anonymize_ip
+    self.enrich_decisions = enrich_decisions
+    self.visitors = visitors
diff --git a/optimizely/event/entity/event_context.py b/optimizely/event/entity/event_context.py
new file mode 100644
index 00000000..5d7efcc5
--- /dev/null
+++ b/optimizely/event/entity/event_context.py
@@ -0,0 +1,27 @@
+# Copyright 2019 Optimizely
+# 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.
+from .. import version
+
+SDK_VERSION = 'python-sdk'
+
+
+class EventContext(object):
+  """ Class respresenting Event Context. """
+
+  def __init__(self, account_id, project_id, revision, anonymize_ip):
+    self.account_id = account_id
+    self.project_id = project_id
+    self.revision = revision
+    self.client_name = SDK_VERSION
+    self.client_version = version.__version__
+    self.anonymize_ip = anonymize_ip
diff --git a/optimizely/event/entity/impression_event.py b/optimizely/event/entity/impression_event.py
new file mode 100644
index 00000000..044fb163
--- /dev/null
+++ b/optimizely/event/entity/impression_event.py
@@ -0,0 +1,25 @@
+# Copyright 2019 Optimizely
+# 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.
+from .user_event import UserEvent
+
+
+class ImpressionEvent(UserEvent):
+  """ Class representing Impression Event. """
+
+  def __init__(self, event_context, user_id, experiment, visitor_attributes, variation, bot_filtering=None):
+    self.event_context = event_context
+    self.user_id = user_id
+    self.experiment = experiment
+    self.visitor_attributes = visitor_attributes
+    self.variation = variation
+    self.bot_filtering = bot_filtering
diff --git a/optimizely/event/entity/snapshot.py b/optimizely/event/entity/snapshot.py
new file mode 100644
index 00000000..726eccdb
--- /dev/null
+++ b/optimizely/event/entity/snapshot.py
@@ -0,0 +1,18 @@
+# Copyright 2019 Optimizely
+# 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.
+
+
+class Snapshot(object):
+  def __init__(self, events, decisions=None):
+    self.events = events
+    self.decisions = decisions
diff --git a/optimizely/event/entity/snapshot_event.py b/optimizely/event/entity/snapshot_event.py
new file mode 100644
index 00000000..ef2bdf8a
--- /dev/null
+++ b/optimizely/event/entity/snapshot_event.py
@@ -0,0 +1,25 @@
+# Copyright 2019 Optimizely
+# 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.
+
+
+class SnapshotEvent(object):
+  """ Class representing Snapshot Event. """
+
+  def __init__(self, entity_id, uuid, key, timestamp, revenue=None, value=None, tags=None):
+    self.entity_id = entity_id
+    self.uuid = uuid
+    self.key = key
+    self.timestamp = timestamp
+    self.revenue = revenue
+    self.value = value
+    self.tags = tags
diff --git a/optimizely/event/entity/user_event.py b/optimizely/event/entity/user_event.py
new file mode 100644
index 00000000..a6343d0d
--- /dev/null
+++ b/optimizely/event/entity/user_event.py
@@ -0,0 +1,29 @@
+# Copyright 2019 Optimizely
+# 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.
+import time
+import uuid
+
+
+class UserEvent(object):
+  """ Class respresenting Event Context. """
+
+  def __init__(self, event_context):
+    self.event_context = event_context
+    self.uuid = self._get_uuid()
+    self.timestamp = self._get_time()
+
+  def _get_time(self):
+    return int(round(time.time() * 1000))
+
+  def _get_uuid(self):
+    return str(uuid.uuid4())
diff --git a/optimizely/event/entity/visitor.py b/optimizely/event/entity/visitor.py
new file mode 100644
index 00000000..d9886b0e
--- /dev/null
+++ b/optimizely/event/entity/visitor.py
@@ -0,0 +1,19 @@
+# Copyright 2019 Optimizely
+# 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.
+
+
+class Visitor(object):
+  def __init__(self, snapshots, attributes, visitor_id):
+    self.snapshots = snapshots
+    self.attributes = attributes
+    self.visitor_id = visitor_id
diff --git a/optimizely/event/entity/visitor_attribute.py b/optimizely/event/entity/visitor_attribute.py
new file mode 100644
index 00000000..cafe58c5
--- /dev/null
+++ b/optimizely/event/entity/visitor_attribute.py
@@ -0,0 +1,20 @@
+# Copyright 2019 Optimizely
+# 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.
+
+
+class VisitorAttribute(object):
+  def __init__(self, entity_id, key, event_type, value):
+    self.entity_id = entity_id
+    self.key = key
+    self.type = event_type
+    self.value = value
diff --git a/tests/test_event_entities.py b/tests/test_event_entities.py
new file mode 100644
index 00000000..8b12d461
--- /dev/null
+++ b/tests/test_event_entities.py
@@ -0,0 +1,162 @@
+# Copyright 2019, Optimizely
+# 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.
+import json
+
+from operator import itemgetter
+
+from optimizely import version
+from optimizely.event.entity import event_batch
+from optimizely.event.entity import visitor_attribute
+from optimizely.event.entity import snapshot_event
+from optimizely.event.entity import visitor
+from optimizely.event.entity import decision
+from optimizely.event.entity import snapshot
+from . import base
+
+
+class EventEntitiesTest(base.BaseTest):
+  def _validate_event_object(self, expected_params, event_obj):
+    """ Helper method to validate properties of the event object. """
+
+    expected_params['visitors'][0]['attributes'] = \
+      sorted(expected_params['visitors'][0]['attributes'], key=itemgetter('key'))
+    event_obj['visitors'][0]['attributes'] = \
+      sorted(event_obj['visitors'][0]['attributes'], key=itemgetter('key'))
+    self.assertEqual(expected_params, event_obj)
+
+  def dict_clean(self, obj):
+    """ Helper method to remove keys from dictionary with None values. """
+
+    result = {}
+    for k, v in obj:
+      if v is None and k in ['revenue', 'value', 'tags']:
+        continue
+      else:
+        result[k] = v
+    return result
+
+  def TestImpressionEventEqualsSerializedPayload(self):
+    expected_params = {
+      'account_id': '12001',
+      'project_id': '111001',
+      'visitors': [{
+        'visitor_id': 'test_user',
+        'attributes': [{
+          'type': 'custom',
+          'value': 'test_value',
+          'entity_id': '111094',
+          'key': 'test_attribute'
+        }],
+        'snapshots': [{
+          'decisions': [{
+            'variation_id': '111129',
+            'experiment_id': '111127',
+            'campaign_id': '111182'
+          }],
+          'events': [{
+            'timestamp': 42123,
+            'entity_id': '111182',
+            'uuid': 'a68cf1ad-0393-4e18-af87-efe8f01a7c9c',
+            'key': 'campaign_activated'
+          }]
+        }]
+      }],
+      'client_name': 'python-sdk',
+      'client_version': version.__version__,
+      'enrich_decisions': True,
+      'anonymize_ip': False,
+      'revision': '42'
+    }
+
+    batch = event_batch.EventBatch("12001", "111001", "42", "python-sdk", version.__version__,
+                                    False, True)
+    visitor_attr = visitor_attribute.VisitorAttribute("111094", "test_attribute", "custom", "test_value")
+    event = snapshot_event.SnapshotEvent("111182", "a68cf1ad-0393-4e18-af87-efe8f01a7c9c", "campaign_activated",
+                                          42123)
+    event_decision = decision.Decision("111182", "111127", "111129")
+
+    snapshots = snapshot.Snapshot([event], [event_decision])
+    user = visitor.Visitor([snapshots], [visitor_attr], "test_user")
+
+    batch.visitors = [user]
+
+    self.maxDiff = None
+    self._validate_event_object(expected_params,
+                                json.loads(
+                                  json.dumps(batch.__dict__, default=lambda o: o.__dict__),
+                                  object_pairs_hook=self.dict_clean
+                                ))
+
+  def TestConversionEventEqualsSerializedPayload(self):
+    expected_params = {
+      'account_id': '12001',
+      'project_id': '111001',
+      'visitors': [{
+        'visitor_id': 'test_user',
+        'attributes': [{
+          'type': 'custom',
+          'value': 'test_value',
+          'entity_id': '111094',
+          'key': 'test_attribute'
+        }, {
+          'type': 'custom',
+          'value': 'test_value2',
+          'entity_id': '111095',
+          'key': 'test_attribute2'
+        }],
+        'snapshots': [{
+          'decisions': [{
+            'variation_id': '111129',
+            'experiment_id': '111127',
+            'campaign_id': '111182'
+          }],
+          'events': [{
+            'timestamp': 42123,
+            'entity_id': '111182',
+            'uuid': 'a68cf1ad-0393-4e18-af87-efe8f01a7c9c',
+            'key': 'campaign_activated',
+            'revenue': 4200,
+            'tags': {
+              'non-revenue': 'abc',
+              'revenue': 4200,
+              'value': 1.234
+            },
+            'value': 1.234
+          }]
+        }]
+      }],
+      'client_name': 'python-sdk',
+      'client_version': version.__version__,
+      'enrich_decisions': True,
+      'anonymize_ip': False,
+      'revision': '42'
+    }
+
+    batch = event_batch.EventBatch("12001", "111001", "42", "python-sdk", version.__version__,
+                                    False, True)
+    visitor_attr_1 = visitor_attribute.VisitorAttribute("111094", "test_attribute", "custom", "test_value")
+    visitor_attr_2 = visitor_attribute.VisitorAttribute("111095", "test_attribute2", "custom", "test_value2")
+    event = snapshot_event.SnapshotEvent("111182", "a68cf1ad-0393-4e18-af87-efe8f01a7c9c", "campaign_activated",
+                                          42123, 4200, 1.234, {'revenue': 4200, 'value': 1.234, 'non-revenue': 'abc'})
+    event_decision = decision.Decision("111182", "111127", "111129")
+
+    snapshots = snapshot.Snapshot([event], [event_decision])
+    user = visitor.Visitor([snapshots], [visitor_attr_1, visitor_attr_2], "test_user")
+
+    batch.visitors = [user]
+
+    self._validate_event_object(expected_params,
+                                json.loads(
+                                  json.dumps(batch.__dict__, default=lambda o: o.__dict__),
+                                  object_pairs_hook=self.dict_clean
+                                ))