As the plethora of mobile apps continues to grow, app publishers are increasingly ask the question - what can I do to have a successful app? In this report, we adopt theoretical lens from transaction cost theory and economic utility in the development and test of a model that examines the impacts of app diversity and app cohesivity on app success. Using data gathered from the Microsoft Windows Phone App distribution platform, our main conclusions are as follows: app diversity (the number of geographic locales an app is built to support) is of particular significance as a potential driver of app success within platforms and app cohesivity (a measure of integration with the platforms services) is positively associated with app success (its download count/rank within the platform). Interestingly, both relationships appear to be moderated by the pricing scheme (free/paid) adopted by publishers for that app.