diff --git a/builtin/providers/aws/resource_aws_elasticache_cluster.go b/builtin/providers/aws/resource_aws_elasticache_cluster.go
index 48b8db0da..54406fdc3 100644
--- a/builtin/providers/aws/resource_aws_elasticache_cluster.go
+++ b/builtin/providers/aws/resource_aws_elasticache_cluster.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/awserr"
+        "github.com/aws/aws-sdk-go/aws/awsutil"
 	"github.com/aws/aws-sdk-go/service/elasticache"
 	"github.com/aws/aws-sdk-go/service/iam"
 	"github.com/hashicorp/terraform/helper/hashcode"
@@ -32,7 +33,6 @@ func resourceAwsElasticacheCluster() *schema.Resource {
 			"engine": &schema.Schema{
 				Type:     schema.TypeString,
 				Required: true,
-				ForceNew: true,
 			},
 			"node_type": &schema.Schema{
 				Type:     schema.TypeString,
@@ -42,13 +42,11 @@ func resourceAwsElasticacheCluster() *schema.Resource {
 			"num_cache_nodes": &schema.Schema{
 				Type:     schema.TypeInt,
 				Required: true,
-				ForceNew: true,
 			},
 			"parameter_group_name": &schema.Schema{
 				Type:     schema.TypeString,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
 			},
 			"port": &schema.Schema{
 				Type:     schema.TypeInt,
@@ -59,7 +57,6 @@ func resourceAwsElasticacheCluster() *schema.Resource {
 				Type:     schema.TypeString,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
 			},
 			"subnet_group_name": &schema.Schema{
 				Type:     schema.TypeString,
@@ -81,7 +78,6 @@ func resourceAwsElasticacheCluster() *schema.Resource {
 				Type:     schema.TypeSet,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
 				Elem:     &schema.Schema{Type: schema.TypeString},
 				Set: func(v interface{}) int {
 					return hashcode.String(v.(string))
@@ -110,6 +106,15 @@ func resourceAwsElasticacheCluster() *schema.Resource {
 			},
 
 			"tags": tagsSchema(),
+
+                        // apply_immediately is used to determine when the update modifications
+                        // take place.
+                        // See http://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_ModifyCacheCluster.html
+                        "apply_immediately": &schema.Schema{
+                                Type:     schema.TypeBool,
+                                Optional: true,
+                                Computed: true,
+                        },
 		},
 	}
 }
@@ -240,6 +245,43 @@ func resourceAwsElasticacheClusterUpdate(d *schema.ResourceData, meta interface{
 			return err
 		}
 	}
+
+        req := &elasticache.ModifyCacheClusterInput{
+                CacheClusterID:   aws.String(d.Id()),
+                ApplyImmediately: aws.Boolean(d.Get("apply_immediately").(bool)),
+        }
+
+        requestUpdate := false
+        if d.HasChange("security_group_ids") {
+                if attr := d.Get("security_group_ids").(*schema.Set); attr.Len() > 0 {
+                        req.SecurityGroupIDs = expandStringList(attr.List())
+                        requestUpdate = true
+                }
+        }
+
+        if d.HasChange("parameter_group_name") {
+                req.CacheParameterGroupName = aws.String(d.Get("parameter_group_name").(string))
+                requestUpdate = true
+        }
+
+        if d.HasChange("engine_version") {
+                req.EngineVersion = aws.String(d.Get("engine_version").(string))
+                requestUpdate = true
+        }
+
+        if d.HasChange("num_cache_nodes") {
+                req.NumCacheNodes = aws.Long(int64(d.Get("num_cache_nodes").(int)))
+                requestUpdate = true
+        }
+
+        if requestUpdate {
+                log.Printf("[DEBUG] Modifying ElastiCache Cluster (%s), opts:\n%s", d.Id(), awsutil.StringValue(req))
+                _, err := conn.ModifyCacheCluster(req)
+                if err != nil {
+                        return fmt.Errorf("[WARN] Error updating ElastiCache cluster (%s), error: %s", d.Id(), err)
+                }
+        }
+
 	return resourceAwsElasticacheClusterRead(d, meta)
 }
 
@@ -252,7 +294,7 @@ func setCacheNodeData(d *schema.ResourceData, c *elasticache.CacheCluster) error
 
 	for _, node := range sortedCacheNodes {
 		if node.CacheNodeID == nil || node.Endpoint == nil || node.Endpoint.Address == nil || node.Endpoint.Port == nil {
-			return fmt.Errorf("Unexpected nil pointer in: %#v", node)
+                        return fmt.Errorf("Unexpected nil pointer in: %s", awsutil.StringValue(node))
 		}
 		cacheNodeData = append(cacheNodeData, map[string]interface{}{
 			"id":      *node.CacheNodeID,
diff --git a/website/source/docs/providers/aws/r/elasticache_cluster.html.markdown b/website/source/docs/providers/aws/r/elasticache_cluster.html.markdown
index 809c18d07..f830abcf2 100644
--- a/website/source/docs/providers/aws/r/elasticache_cluster.html.markdown
+++ b/website/source/docs/providers/aws/r/elasticache_cluster.html.markdown
@@ -60,6 +60,10 @@ names to associate with this cache cluster
 * `security_group_ids` – (Optional, VPC only) One or more VPC security groups associated
  with the cache cluster
 
+* `apply_immediately` - (Optional) Specifies whether any database modifications
+     are applied immediately, or during the next maintenance window. Default is
+     `false`. See [Amazon ElastiCache Documentation for more information.][1]
+
 * `tags` - (Optional) A mapping of tags to assign to the resource.
 
 
@@ -69,3 +73,5 @@ The following attributes are exported:
 
 * `cache_nodes` - List of node objects including `id`, `address` and `port`.
    Referenceable e.g. as `${aws_elasticache_cluster.bar.cache_nodes.0.address}`
+
+[1]: http://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_ModifyCacheCluster.html