diff --git a/README.md b/README.md
index fa5d2d0..a7aa6ef 100644
--- a/README.md
+++ b/README.md
@@ -90,7 +90,9 @@ func main() {
     r := redis.NewClient(&redis.Options{
         Addr: "localhost:6379",
     }
-    bg := asynq.NewBackground(r, 10)
+    bg := asynq.NewBackground(r, &asynq.Config{
+        Concurrency: 20,
+    })
 
     // Blocks until signal TERM or INT is received.
     // For graceful shutdown, send signal TSTP to stop processing more tasks
@@ -136,7 +138,9 @@ func main() {
     r := redis.NewClient(&redis.Options{
         Addr: "localhost:6379",
     }
-    bg := asynq.NewBackground(r, 10)
+    bg := asynq.NewBackground(r, &asynq.Config{
+        Concurrency: 20,
+    })
 
     // Use asynq.HandlerFunc adapter for a handler function
     bg.Run(asynq.HandlerFunc(handler))
diff --git a/background.go b/background.go
index 9d5b719..bfa4caa 100644
--- a/background.go
+++ b/background.go
@@ -33,12 +33,29 @@ type Background struct {
 	processor *processor
 }
 
-// NewBackground returns a new Background with the specified number of workers
-// given a redis configuration .
-func NewBackground(r *redis.Client, numWorkers int) *Background {
+// Config specifies the background-task processing behavior.
+type Config struct {
+	// Max number of concurrent workers to process tasks.
+	//
+	// If set to zero or negative value, NewBackground will overwrite the value to one.
+	Concurrency int
+
+	// TODO(hibiken): Add ShutdownTimeout
+	// ShutdownTimeout time.Duration
+
+	// TODO(hibiken): Add RetryDelayFunc
+}
+
+// NewBackground returns a new Background instance given a redis client
+// and background processing configuration.
+func NewBackground(r *redis.Client, cfg *Config) *Background {
+	n := cfg.Concurrency
+	if n < 1 {
+		n = 1
+	}
 	rdb := rdb.NewRDB(r)
 	scheduler := newScheduler(rdb, 5*time.Second)
-	processor := newProcessor(rdb, numWorkers, nil)
+	processor := newProcessor(rdb, n, nil)
 	return &Background{
 		rdb:       rdb,
 		scheduler: scheduler,
diff --git a/background_test.go b/background_test.go
index 489bebc..5b648ca 100644
--- a/background_test.go
+++ b/background_test.go
@@ -18,7 +18,9 @@ func TestBackground(t *testing.T) {
 		DB:   15,
 	})
 	client := NewClient(r)
-	bg := NewBackground(r, 10)
+	bg := NewBackground(r, &Config{
+		Concurrency: 10,
+	})
 
 	// no-op handler
 	h := func(task *Task) error {
diff --git a/client.go b/client.go
index e51e385..ac6afd8 100644
--- a/client.go
+++ b/client.go
@@ -25,7 +25,7 @@ func NewClient(r *redis.Client) *Client {
 	return &Client{rdb}
 }
 
-// Option configures the behavior of task processing.
+// Option specifies the processing behavior for the associated task.
 type Option interface{}
 
 // max number of times a task will be retried.
diff --git a/doc.go b/doc.go
index 1836fb4..7e08e11 100644
--- a/doc.go
+++ b/doc.go
@@ -3,9 +3,7 @@ Package asynq provides a framework for background task processing.
 
 The Client is used to register a task to be processed at the specified time.
 
-	client := asynq.NewClient(&asynq.RedisConfig{
-	    Addr: "localhost:6379",
-	})
+	client := asynq.NewClient(redis)
 
 	t := &asynq.Task{
 	    Type:    "send_email",
@@ -16,8 +14,8 @@ The Client is used to register a task to be processed at the specified time.
 
 The Background is used to run the background processing with a given
 handler with the specified number of workers.
-    bg := asynq.NewBackground(20, &asynq.RedisConfig{
-        Addr: "localhost:6379",
+    bg := asynq.NewBackground(redis, &asynq.Config{
+        Concurrency: 20,
     })
 
     bg.Run(handler)