Autonomy is the sense that one has control over one’s actions within an environment or that one has some degree of choice over his or her own life. Autonomy support involves an individual who is in a position of authority, (e.g., parent, teacher, coach), taking the perspective of another (e.g. student, child), acknowledging their feelings, and providing opportunities for choice (Reeve, Jang, Carrell, Jeon & Barch, 2004; Roth, Assor, Kanat-Maymon, & Kaplan, 2007). STEAM is a curricular framework that emphasizes project-based learning through the integration of science, technology, engineering, arts and mathematics. This study examined the beliefs and practices of third to fifth grade teachers around student autonomy during STEAM instruction. To meet this purpose, a qualitative analysis of teachers’ epistemological beliefs, classroom instructional practices, and use of autonomy-supportive practices during STEAM instruction was conducted. Next, an examination of students’ perception of and response to autonomy-supportive practices during instruction was conducted using student survey data and coded observations. A belief/practice gap was found among teachers as reported beliefs and teacher practices were qualitatively different. Hierarchical linear modeling was used to examine the impact of student’s perceptions of autonomy, attitudes toward STEAM and teacher’s autonomous practices on student engagement Student perceptions of autonomy and attitudes towards STEAM were found to be significant predictors of student engagement by homeroom, but teacher’s autonomous practices were not at the student level or the teacher level.