Reference: http://stackoverflow.com/questions/19898456/cant-find-import-module-option-in-project-structure-android-studio-0-3-4-0-5

Using module

For android studio 0.5.7, volley was successfully imported as a library project following these steps:

Create a directory named "libraries"(whichever you want) under your project root
Clone volley using git under the directory created in step 1, command is "git clone https://android.googlesource.com/platform/frameworks/volley". Now the project structure looks like:

[Project root]
|- [Your module]
|- libraries
   |- volley
Import volley through : Right click project root -> Open Module Settings -> Click "+"(New Module) in the up left corner -> Import existing project -> Select volley source directory -> Next After step 3, volley is imported, but dependency on library project volley is not setup yet.
Setup module dependency : Right click project root -> Open Module Settings(Now volley should appear in the module list) -> Choose [Your module] -> Switch to tab "Dependencies" -> Click "+"(Add) in the left bottom corner -> Choose "Module dependency" -> Select ":volley" in the module list dialog
Now everything works fine, you can use volley as you want