diff --git a/pkg/client/counter/counter.go b/pkg/client/counter/counter.go
index f701d89..f3244b8 100644
--- a/pkg/client/counter/counter.go
+++ b/pkg/client/counter/counter.go
@@ -16,6 +16,7 @@ package counter
 
 import (
 	"context"
+
 	api "github.com/atomix/api/proto/atomix/counter"
 	"github.com/atomix/api/proto/atomix/headers"
 	"github.com/atomix/go-client/pkg/client/primitive"
@@ -47,6 +48,9 @@ type Counter interface {
 
 	// Decrement decrements the counter by the given delta
 	Decrement(ctx context.Context, delta int64) (int64, error)
+
+	// CAS checks the counter value and then updates its current value
+	CAS(ctx context.Context, expect int64, update int64) (bool, error)
 }
 
 // New creates a new counter for the given partitions
@@ -149,6 +153,26 @@ func (c *counter) Decrement(ctx context.Context, delta int64) (int64, error) {
 	return response.(*api.DecrementResponse).NextValue, nil
 }
 
+func (c *counter) CAS(ctx context.Context, expect int64, update int64) (bool, error) {
+	response, err := c.instance.DoCommand(ctx, func(ctx context.Context, conn *grpc.ClientConn, header *headers.RequestHeader) (*headers.ResponseHeader, interface{}, error) {
+		client := api.NewCounterServiceClient(conn)
+		request := &api.CheckAndSetRequest{
+			Header: header,
+			Expect: expect,
+			Update: update,
+		}
+		response, err := client.CheckAndSet(ctx, request)
+		if err != nil {
+			return nil, nil, err
+		}
+		return response.Header, response, nil
+	})
+	if err != nil {
+		return false, err
+	}
+	return response.(*api.CheckAndSetResponse).Succeeded, nil
+}
+
 func (c *counter) Close(ctx context.Context) error {
 	return c.instance.Close(ctx)
 }
diff --git a/pkg/client/counter/counter_test.go b/pkg/client/counter/counter_test.go
index eafea4d..97028b6 100644
--- a/pkg/client/counter/counter_test.go
+++ b/pkg/client/counter/counter_test.go
@@ -16,10 +16,11 @@ package counter
 
 import (
 	"context"
+	"testing"
+
 	"github.com/atomix/go-client/pkg/client/primitive"
 	"github.com/atomix/go-client/pkg/client/test"
 	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 func TestCounterOperations(t *testing.T) {
@@ -69,6 +70,18 @@ func TestCounterOperations(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, int64(10), value)
 
+	casValue, err := counter.CAS(context.TODO(), 15, 25)
+	assert.NoError(t, err)
+	assert.Equal(t, false, casValue)
+
+	casValue, err = counter.CAS(context.TODO(), 10, 20)
+	assert.NoError(t, err)
+	assert.Equal(t, true, casValue)
+
+	value, err = counter.Get(context.TODO())
+	assert.NoError(t, err)
+	assert.Equal(t, int64(20), value)
+
 	err = counter.Close(context.Background())
 	assert.NoError(t, err)
 
@@ -80,7 +93,7 @@ func TestCounterOperations(t *testing.T) {
 
 	value, err = counter1.Get(context.TODO())
 	assert.NoError(t, err)
-	assert.Equal(t, int64(10), value)
+	assert.Equal(t, int64(20), value)
 
 	err = counter1.Close(context.Background())
 	assert.NoError(t, err)
diff --git a/pkg/client/list/list.go b/pkg/client/list/list.go
index 2592353..42e2100 100644
--- a/pkg/client/list/list.go
+++ b/pkg/client/list/list.go
@@ -18,6 +18,7 @@ import (
 	"context"
 	"encoding/base64"
 	"errors"
+
 	"github.com/atomix/api/proto/atomix/headers"
 	api "github.com/atomix/api/proto/atomix/list"
 	"github.com/atomix/go-client/pkg/client/primitive"
@@ -58,6 +59,9 @@ type List interface {
 	// Len gets the length of the list
 	Len(ctx context.Context) (int, error)
 
+	// Contains checks whether the list contains a value
+	Contains(ctx context.Context, value []byte) (bool, error)
+
 	// Slice returns a slice of the list from the given start index to the given end index
 	Slice(ctx context.Context, from int, to int) (List, error)
 
@@ -258,6 +262,25 @@ func (l *list) Remove(ctx context.Context, index int) ([]byte, error) {
 	}
 }
 
+func (l *list) Contains(ctx context.Context, value []byte) (bool, error) {
+	response, err := l.instance.DoQuery(ctx, func(ctx context.Context, conn *grpc.ClientConn, header *headers.RequestHeader) (*headers.ResponseHeader, interface{}, error) {
+		client := api.NewListServiceClient(conn)
+		request := &api.ContainsRequest{
+			Header: header,
+			Value:  base64.StdEncoding.EncodeToString(value),
+		}
+		response, err := client.Contains(ctx, request)
+		if err != nil {
+			return nil, nil, err
+		}
+		return response.Header, response, nil
+	})
+	if err != nil {
+		return false, err
+	}
+	return bool(response.(*api.ContainsResponse).Contains), nil
+}
+
 func (l *list) Len(ctx context.Context) (int, error) {
 	response, err := l.instance.DoQuery(ctx, func(ctx context.Context, conn *grpc.ClientConn, header *headers.RequestHeader) (*headers.ResponseHeader, interface{}, error) {
 		client := api.NewListServiceClient(conn)
diff --git a/pkg/client/list/list_test.go b/pkg/client/list/list_test.go
index 41ba7e4..1c7946d 100644
--- a/pkg/client/list/list_test.go
+++ b/pkg/client/list/list_test.go
@@ -16,10 +16,11 @@ package list
 
 import (
 	"context"
+	"testing"
+
 	"github.com/atomix/go-client/pkg/client/primitive"
 	"github.com/atomix/go-client/pkg/client/test"
 	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 func TestListOperations(t *testing.T) {
@@ -53,6 +54,10 @@ func TestListOperations(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "foo", string(value))
 
+	contain, err := list.Contains(context.TODO(), []byte("foo"))
+	assert.NoError(t, err)
+	assert.Equal(t, true, contain)
+
 	err = list.Append(context.TODO(), []byte("bar"))
 	assert.NoError(t, err)
 
diff --git a/pkg/client/list/slice.go b/pkg/client/list/slice.go
index 992e75c..a9b3132 100644
--- a/pkg/client/list/slice.go
+++ b/pkg/client/list/slice.go
@@ -17,6 +17,7 @@ package list
 import (
 	"context"
 	"errors"
+
 	"github.com/atomix/go-client/pkg/client/primitive"
 )
 
@@ -96,6 +97,11 @@ func (l *slicedList) Len(ctx context.Context) (int, error) {
 	return size, nil
 }
 
+func (l *slicedList) Contains(ctx context.Context, value []byte) (bool, error) {
+	contain, err := l.list.Contains(ctx, value)
+	return contain, err
+}
+
 func (l *slicedList) Slice(ctx context.Context, from int, to int) (List, error) {
 	if l.from != nil {
 		from += *l.from