I have just downloaded Android Studio 1.0.1 and this is the new project structure
First you have to add library project (module) in Android Studio
File -> Import Module
To add library project (module) in build path, click
File -> Project Structure
On the left hand side click on
app -> Dependencies tab -> green + button -> Module dependency
Now select the library project you already added.
For more details refer this link
In My Case to add external library project into android studio 1.1.0
step-1 : File -> Import Module -> set path for library project
step-2 : Set dependencies{} in main projects's build.gradle like,
dependencies {
compile project(':facebookSDK')
compile project(':slidingMenu')
compile project(':SkyconsLibrary')
}