This study capitalizes on a unique, nested data set comprised of students (n = 531) and teachers (n = 45) in three high schools that explicitly incorporated student support roles into teachers' job descriptions. Drawing from research on student-teacher relationships, teacher effects on student outcomes, and role theory, this study explored correlates of teachers' role definition. In particular, it considered role breadth, or the degree to which teachers defined their roles to include the provision of various forms of social and emotional support to students. We hypothesized that teachers' role breadth would relate to student perceptions of teacher support and high academic expectations (also known as academic press). Multi-level modeling of the relationship between teacher role breadth and student outcomes accounted for the data's nested quality and showed a positive relationship between teachers' sense of efficacy about providing student support and their reported role breadth. In addition, teacher role breadth was positively related to student perceptions of teacher support and academic press, controlling for student-reported background and school performance characteristics. Implications for student-teacher relationships, teacher education, and teacher roles are discussed.