This talk covers a successful utilization of Rails Engines to share features that cut across the layers of MVC in different Rails 3 projects. Rails Engines thus provide the best of both worlds: improved productivity by reusing MVC code (including assets like Javascript, CSS, and Images) and better flexibility by allowing different applications to customize behavior as needed without reliance on application-dependent conditionals. Rails Engine patterns will be provided to guide developers on how to leverage Rails Engines' reusability and flexibility without sacrificing maintainability. Outline: Basics of Rails Engines Rails Engine Patterns Improved Productivity Tips Summary of Benefits and Trade-Offs Attendees should walk away with an overview of Rails Engines and guidelines on how to utilize them effectively.