Uncovering how teachers' beliefs about teaching and learning influence their instructional practices and students' goals in the classroom is important for understanding how to create learning environments focused on mastery and understanding. Most of the previous research on this topic has investigated these relationships in teachers, classrooms and students at either the elementary, middle or college level. Using this research as a guide, the current investigation examined relationships among teacher beliefs, instructional practices and classroom goal orientations in high school science classrooms. Path analysis techniques were used to analyze responses and revealed that personal teaching efficacy and teachers' perceptions of a supportive school culture were related to teachers' use of instructional practices focused on task mastery and understanding. Teachers' perceptions of a supportive school culture were also related to teachers' use of instructional practices focused on competition and to students' perceptions of a mastery classroom goal orientation. The use of practices focused on demonstrating ability was related to perceptions of a competitive school culture. In light of these findings, the applicability of research findings from the elementary and middle school settings is discussed, along with how the unique nature of the high school learning environment may explain these findings.