Today, the Annenberg Innovation Lab at USC and the Joan Ganz Cooney Center announced the release of "T is for Transmedia: Learning Through Transmedia Play." The report is written by Becky Herr-Stephenson and Meryl Alper, under the supervision of Erin Reilly. This paper provides a much-needed guidebook to transmedia in the lives of children age 5-11 and its applications to storytelling, play, and learning. Building off of a review of the existing popular and scholarly literature about transmedia and children, this report identifies key links between transmedia and learning, highlights key characteristics of transmedia play, and presents core principles for and extended case studies of meaningful transmedia play experiences.