Enterprise applications now span multiple platforms, and there is an opportunity to write them all in .NET using Microsoft and Xamarin tools. With this opportunity there is an increased benefit in sharing code and logic for these different platforms. We will be looking at how code linking, universal shared projects and PCLs can help write logic once and run on different platforms like Windows Store Applications, Xamarin iOS, Xamarin Android and Windows Phone. We will also look at the PCL bait and switch method to allow platform specific libraries written with the same interface to be referenced by PCLs. Finally we will look at how MVVM frameworks like MVVM Cross can help use the same logic for the platforms you target.