As social media use explodes in popularity, teachers can now share resources and interact with a broad international audience of colleagues, scholars, students, and the general public. Teachers use sites such as Twitter to develop and hone their professional identities and manage others’ impressions of them and their work. This text draws on extensive research to provide guidance about teachers’ use of social media for professional development and identity formation. A conceptual framework drawing on Goffman’s Theory of the Presentation of Self in Everyday Life and research into how users interact online informed the case studies of preservice teachers’ experiences with social media. A secondary function of the book is to guide teachers through the process of conducting action research projects in their own classrooms. Use of social media involves more than just sharing links or scattered thoughts; savvy users consider a wide variety of methods and forms of interaction. This text shares research-based best practices for these forms of information sharing, including the effects of these practices on different audiences. Twitter and other forms of social media offer an easily accessible, free mode of communication; however, while asking a question and obtaining answers from people all over the globe is exciting, and while this process can be empowering for both the questioner and the responder, it can also be problematic as viewed from a quality control perspective. Is the information accurate? Does it reflect research-based best practices? What are some of the ways that teachers can and should form personae and identities on social media? What are the risks? This text chips away at these crucial questions.