diff --git a/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts b/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
index 34462984f87fe..a7cbc6b5083f3 100644
--- a/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
+++ b/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
@@ -153,7 +153,8 @@ export class AutoScalingGroup extends cdk.Construct implements ec2.IClassicLoadB
 
     private readonly userDataLines = new Array<string>();
     private readonly autoScalingGroup: cloudformation.AutoScalingGroupResource;
-    private readonly securityGroup: ec2.SecurityGroup;
+    private readonly securityGroup: ec2.SecurityGroupRef;
+    private readonly securityGroups: ec2.SecurityGroupRef[] = [];
     private readonly loadBalancerNames: cdk.Token[] = [];
 
     constructor(parent: cdk.Construct, name: string, props: AutoScalingGroupProps) {
@@ -161,6 +162,7 @@ export class AutoScalingGroup extends cdk.Construct implements ec2.IClassicLoadB
 
         this.securityGroup = new ec2.SecurityGroup(this, 'InstanceSecurityGroup', { vpc: props.vpc });
         this.connections = new ec2.Connections({ securityGroup: this.securityGroup });
+        this.securityGroups.push(this.securityGroup);
 
         if (props.allowAllOutbound !== false) {
             this.connections.allowTo(new ec2.AnyIPv4(), new ec2.AllConnections(), 'Outbound traffic allowed by default');
@@ -177,12 +179,13 @@ export class AutoScalingGroup extends cdk.Construct implements ec2.IClassicLoadB
         // use delayed evaluation
         const machineImage = props.machineImage.getImage(this);
         const userDataToken = new cdk.Token(() => new cdk.FnBase64((machineImage.os.createUserData(this.userDataLines))));
+        const securityGroupsToken = new cdk.Token(() => this.securityGroups.map((sg) => sg.securityGroupId));
 
         const launchConfig = new cloudformation.LaunchConfigurationResource(this, 'LaunchConfig', {
             imageId: machineImage.imageId,
             keyName: props.keyName,
             instanceType: props.instanceType.toString(),
-            securityGroups: [this.securityGroup.securityGroupId],
+            securityGroups: securityGroupsToken,
             iamInstanceProfile: iamProfile.ref,
             userData: userDataToken
         });
@@ -227,6 +230,15 @@ export class AutoScalingGroup extends cdk.Construct implements ec2.IClassicLoadB
         this.applyUpdatePolicies(props);
     }
 
+    /**
+     * Attach the security group to all instances in this autoscaling group
+     *
+     * @param securityGroup: The SecurityGroupRef to add
+     */
+    public attachSecurityGroup(securityGroup: ec2.SecurityGroupRef): void {
+        this.securityGroups.push(securityGroup);
+    }
+
     public attachToClassicLB(loadBalancer: ec2.ClassicLoadBalancer): void {
         this.loadBalancerNames.push(loadBalancer.loadBalancerName);
     }
diff --git a/packages/@aws-cdk/aws-autoscaling/test/test.auto-scaling-group.ts b/packages/@aws-cdk/aws-autoscaling/test/test.auto-scaling-group.ts
index 5deccbfbe8d5b..4d0b04f310315 100644
--- a/packages/@aws-cdk/aws-autoscaling/test/test.auto-scaling-group.ts
+++ b/packages/@aws-cdk/aws-autoscaling/test/test.auto-scaling-group.ts
@@ -332,6 +332,30 @@ export = {
 
       test.done();
     },
+    'can add Security Group to Fleet'(test: Test) {
+        // GIVEN
+        const stack = new cdk.Stack(undefined, 'MyStack', { env: { region: 'us-east-1', account: '1234' }});
+        const vpc = mockVpc(stack);
+
+        // WHEN
+        const asg = new autoscaling.AutoScalingGroup(stack, 'MyFleet', {
+            instanceType: new ec2.InstanceTypePair(ec2.InstanceClass.M4, ec2.InstanceSize.Micro),
+            machineImage: new ec2.AmazonLinuxImage(),
+            vpc,
+        });
+        asg.attachSecurityGroup(mockSecurityGroup(stack));
+        expect(stack).to(haveResource("AWS::AutoScaling::LaunchConfiguration", {
+            SecurityGroups: [
+                {
+                    "Fn::GetAtt": [
+                        "MyFleetInstanceSecurityGroup774E8234",
+                        "GroupId"
+                    ]
+                },
+                'most-secure'],
+        }));
+        test.done();
+    },
 };
 
 function mockVpc(stack: cdk.Stack) {
@@ -342,3 +366,9 @@ function mockVpc(stack: cdk.Stack) {
         privateSubnetIds: [ new ec2.VpcSubnetId('pri1') ],
     });
 }
+
+function mockSecurityGroup(stack: cdk.Stack) {
+    return ec2.SecurityGroupRef.import(stack, 'MySG', {
+        securityGroupId: new ec2.SecurityGroupId('most-secure'),
+    });
+}