The study of peer interaction has a long and rich history. We have long sought to understand how children learn to get along with one another and why this is important. Implicitly and explicitly enmeshed with our studies of peer interaction is the question of children who tend not to interact with peers. In this commentary we trace some of the origins of research on children's social withdrawal. Significantly, this topic was largely nonexistent in the 1950s, 1960s, and 1970s, but it has more recently emerged as a phenomenon that is publication rich, research supported, and much discussed among parents and teachers. In the latter half of this chapter we take stock of current research issues in the etiology of social withdrawal and outline some future directions for researchers to consider.