This chapter is designed to explore socially networked spaces as an important process within teacher professional development. Social networking enables teachers to access new ideas, to collaborate and to contribute to a shared knowledge, regardless of time and place. These factors are significant and necessary in a world where a knowledge building economy is a noteworthy indicator of economic prosperity. To live and prosper in the digital age, to understand and function successfully in online spaces and to be able to be self-directed in our learning is foundational for our current and future worlds. The online world has become an integral part of the physical world and with that has come the need for teachers to be fore-runners in shaping our students to live and learn as a basic necessity. The.rise of social networking with its inherent disposition for sharing and knowledge-producing exchanges logically suggests a merger with education to improve teaching and learning outcomes (Veletsianos, Kimmons and French 2013). Teacher professional development has seen a renaissance, and a shift from training or workshops held on school sites to online environments affirming redefinitions of teacher practices to work in new ways, to work in partnership and better focus on high task complexity and continuous learning (Loveless 2008). To support this re-direction towards an online networked professional learning model, an understanding of the advantages social networking can offer teacher professional development is required. The chapter provides an extensive literature review with illustrations of practice of both the use of social networking in pre-service and in-service teacher professional development contexts that identify relationships and patterns of understanding in each place. What is presented in the chapter are new understandings of the components of effective online professional development in these spaces including critical points for consideration and the dilemmas that can occur around implementation. A final elaboration of what is considered a sustainable and transformative model of online teacher professional development using social networking will be described, illustrating the key elements of effective implementation.