This study describes and explains changes in ninth- and tenth-grade social studies and science courses that emerged in the pedagogy of classroom teachers as a result of participation in a detracking project in an urban high school. The detracking project represented a profound change in the organization of school curricula. Four social studies and four science teachers, and 84 students in 12 classes, 4 college preparatory, 4 untracked, 2 advanced placement, and 2 lowest classes, participated. Qualitative research methodology was used by two researchers independently of each other. They triangulated their data by using descriptive journal entries of classroom interactions, detailed records of interviews and conversations, and specimen data such as lesson plans. The pedagogic factors that emerged as important in the quality of instruction were: (1) teacher- or student-centered instruction; (2) cooperative learning or individual student work; (3) strategies for questioning; (4) verbal interaction in the classroom; and (5) evidence of process skills such as critical thinking or writing. Teachers began to change their practices, using more cooperative learning and more student-centered approaches. Teacher expectations of students of initial lower tracks rose, and teachers cooperated more fully with each other. The changes teachers made for these untracked classes affected their teaching overall. (SLD)