To move composition research forward into the 21st century, research conducted at the National Center for the Study of Writing and Literacy will benefit by continuing to be inclusive--of a diverse population of learners, taught by a diverse population of teachers, using approaches that allow for a diversity of ways of learning. The initial theory underlying the Center's research program was a socio-cognitive theory of writing based on the work of L. S. Vygotsky. Using a Vygotskian theoretical frame, the Center in 1985 conducted a study that compared learning to write in inner city schools in the United States and Great Britain. In the end, Vygotsky's concept of social interaction proved much too general to account for the teaching and learning of writing. By 1990, the Center had expanded its notions of social processes and social interaction to give greater consideration to the cultural meaning of students' experiences. A current project explores the dynamics of learning to write and writing to learn in urban multicultural classrooms. The project involves a national collaboration with teachers who work with Center personnel to conduct research in their own classrooms. The Center's sociocultural frame is proving particularly important in helping researchers understand the needs of ethnically and socioeconomically diverse populations of learners. (Contains 13 references.) (RS)