This article focuses on one theory of school reform that seeks to counteract insularity among teachers with respect to questions of what to teach and how. It networks teachers across schools and gives them access to outside expertise in their content areas. In this approach teacher learning happens within a series of face-to-face and virtual meetings, sometimes over many years. In this article, we focus on teacher networking and, more specifically, on how teacher networks design for teacher learning. By describing several dynamic tensions inherent in the designs of a sample of teacher networks, and by raising questions about these tensions and their relation to teacher learning, we hope to contribute toward the building of a theory of effective network design. We illustrate these design concepts with references to the work of seven networks that aim to revamp teachers' knowledge in the humanities. In the final section of the article, we offer several sets of questions that derive from our analysis and that might form the basis for further research.