Arguing that the use of peer groups in a writing classroom theoretically supports the goals of the paradigm shift from emphasis on written product to writing process that has occurred in recent years, this paper examines the complexities confronting teachers who attempt to use groups for instructional purposes. Following a brief introduction, the first section of the paper traces the emergence of the use of peer groups in the writing classroom, touching upon the shift from product to process to collaboration and upon research in the area of collaborative and group learning. The second section of the paper discusses how language learning theory supports group work. In particular, this section examines the social context of schools and theories of language learning and the various features of collaboration. The third section looks at research on peer response, and the final section discusses future research directions. A five-page list of references concludes the paper. (FL)