This document discusses techniques for designing narratives across multiple platforms, known as transmedia storytelling. It begins by looking at early examples from Hitchcock films and how they engaged audiences through additional materials. It then examines three levels of audience engagement - passive, casual, and active - and how participation has increased with new technologies. Finally, it addresses how to develop the world, mythology, characters, and themes of a transmedia story (the "storyworld") as well as the importance of defining the core narrative and having a clear strategic plan.