Argues that neither traditional "knowledge delivery" models of teaching, nor a purely "student-centered" approach, adequately addresses the challenges of student diversity. Proposes an emphasis on the sociocultural nature of learning and teaching, modeling learning as acquiring the capacity to participate in discourses of an unfamiliar knowledge community, and teaching as supporting that participation. Outlines ways teachers can structure courses so that very diverse cohorts of students can progress together. (EV)