diff --git a/moto/ssm/models.py b/moto/ssm/models.py
index d8dc10a4..0f75599c 100644
--- a/moto/ssm/models.py
+++ b/moto/ssm/models.py
@@ -5,7 +5,9 @@ from collections import defaultdict
 from moto.core import BaseBackend, BaseModel
 from moto.ec2 import ec2_backends
 
+import datetime
 import time
+import uuid
 
 
 class Parameter(BaseModel):
@@ -138,6 +140,39 @@ class SimpleSystemManagerBackend(BaseBackend):
     def list_tags_for_resource(self, resource_type, resource_id):
         return self._resource_tags[resource_type][resource_id]
 
+    def send_command(self, **kwargs):
+        instances = kwargs['InstanceIds']
+        now = datetime.datetime.now()
+        expires_after = now + datetime.timedelta(0, int(kwargs['TimeoutSeconds']))
+        return {
+            'Command': {
+                'CommandId': str(uuid.uuid4()),
+                'DocumentName': kwargs['DocumentName'],
+                'Comment': kwargs.get('Comment'),
+                'ExpiresAfter': expires_after.isoformat(),
+                'Parameters': kwargs['Parameters'],
+                'InstanceIds': kwargs['InstanceIds'],
+                'Targets': kwargs.get('targets'),
+                'RequestedDateTime': now.isoformat(),
+                'Status': 'Success',
+                'StatusDetails': 'string',
+                'OutputS3Region': kwargs.get('OutputS3Region'),
+                'OutputS3BucketName': kwargs.get('OutputS3BucketName'),
+                'OutputS3KeyPrefix': kwargs.get('OutputS3KeyPrefix'),
+                'MaxConcurrency': 'string',
+                'MaxErrors': 'string',
+                'TargetCount': len(instances),
+                'CompletedCount': len(instances),
+                'ErrorCount': 0,
+                'ServiceRole': kwargs.get('ServiceRoleArn'),
+                'NotificationConfig': {
+                    'NotificationArn': 'string',
+                    'NotificationEvents': ['Success'],
+                    'NotificationType': 'Command'
+                }
+            }
+        }
+
 
 ssm_backends = {}
 for region, ec2_backend in ec2_backends.items():
diff --git a/moto/ssm/responses.py b/moto/ssm/responses.py
index 0b4ca3b6..757bf031 100644
--- a/moto/ssm/responses.py
+++ b/moto/ssm/responses.py
@@ -190,3 +190,8 @@ class SimpleSystemManagerResponse(BaseResponse):
         tag_list = [{'Key': k, 'Value': v} for (k, v) in tags.items()]
         response = {'TagList': tag_list}
         return json.dumps(response)
+
+    def send_command(self):
+        return json.dumps(
+            self.ssm_backend.send_command(**self.request_params)
+        )
diff --git a/tests/test_ssm/test_ssm_boto3.py b/tests/test_ssm/test_ssm_boto3.py
index ff8e5e8a..0e8a770b 100644
--- a/tests/test_ssm/test_ssm_boto3.py
+++ b/tests/test_ssm/test_ssm_boto3.py
@@ -458,3 +458,34 @@ def test_add_remove_list_tags_for_resource():
         ResourceType='Parameter'
     )
     len(response['TagList']).should.equal(0)
+
+
+@mock_ssm
+def test_send_command():
+    ssm_document = 'AWS-RunShellScript'
+    params = {'commands': ['#!/bin/bash\necho \'hello world\'']}
+
+    client = boto3.client('ssm', region_name='us-east-1')
+    # note the timeout is determined server side, so this is a simpler check.
+    before = datetime.datetime.now()
+
+    response = client.send_command(
+        InstanceIds=['i-123456'],
+        DocumentName=ssm_document,
+        TimeoutSeconds=60,
+        Parameters=params,
+        OutputS3Region='us-east-2',
+        OutputS3BucketName='the-bucket',
+        OutputS3KeyPrefix='pref'
+    )
+    cmd = response['Command']
+
+    cmd['CommandId'].should_not.be(None)
+    cmd['DocumentName'].should.equal(ssm_document)
+    cmd['Parameters'].should.equal(params)
+
+    cmd['OutputS3Region'].should.equal('us-east-2')
+    cmd['OutputS3BucketName'].should.equal('the-bucket')
+    cmd['OutputS3KeyPrefix'].should.equal('pref')
+
+    cmd['ExpiresAfter'].should.be.greater_than(before)