This presentation will look at the application of social and game mechanics in a sustainable fashion app Closet Swap - an online fashion community for teens to swap clothes with their friends. Closet Swap applies a game and social layer to the real world of fashion. It is a must-have fashion app that influences behavior in a natural way - by celebrating personal style over disposable fashion and getting users to swap, not shop. This talk will look at the design process, audience research and testing and how game and social mechanics were employed to create an experience that is entertaining and authentic to achieve its goal.