A model of the influences on teacher practice and student learning is formulated and illustrated by analyzing the practice of 12 high school history teachers in 6 schools. Since the data base contains both observations of 228 lessons, as well as extensive interviews with teachers and department chairs, it is possible to assess the opportunity for student learning presented by instruction, analyze the degree of consonance between teacher goals and practice, and investigate various explanations for differential opportunity to learn. Teachers at the three schools serving a higher proportion of college bound students were found to include critical thinking and writing skills among their goals, in contrast to the other teachers who focused more narrowly on content goals. The four teachers who appeared most successful at meeting their goals were found in the schools serving primarily college bound students. Differences in teacher practice are explained by school and individual level factors, including school resources, departmental leadership, and teacher content/pedagogic knowledge. Implications of the study for teacher education are discussed. (Author/JD)