An emerging trend in educational research is the use of social network theory and methodology to understand how teacher collaboration can support or constrain teaching, learning, and educational change. This article provides a critical synthesis of educational literature on school social networks among educators to advance our understanding of the embeddedness of teachers in the social context of schools. It focuses on how researchers currently use a social network perspective as a theoretical lens and methodology to frame studies on teacher collaboration in schools. Building on exemplary findings of recent studies, it shows that the pattern of social relationships among teachers may significantly enhance our understanding of the ways in which teacher collaboration takes place and contributes to student learning, teachers' instructional practice, and the implementation of reform. Finally, limitations and future directions in the conceptualization, measurement, and analysis of school social networks are indicated. (Contains 2 tables, 1 figure and 5 notes.)