This chapter provides a review of the theoretical bases and international research on the uses of Web 2.0 applications for learning through collaboration. Web 2.0 applications empower users with a venue for personal expression, sharing, communicating, and collaborating with others, thus offering enriched opportunities for learning. In our review, we found evidence of engaging and effective uses of Web 2.0 applications such as blogs, wikis, collaborative documents and concept mapping, VoiceThread, video sharing applications (e.g., YouTube), microblogging (e.g., Twitter), social networking sites, and social bookmarking that applied contemporary and foundational educational theory. We also identified opportunities and challenges associated with learning through collaboration with Web 2.0 applications, which can inform research directions and areas to explore for ECT researchers.