The Supporting Effective Teaching (SET) project consists of studies that examine the relationship between elementary general education teachers' beliefs about disability and ability and their roles in inclusive classrooms, and how these are related to teaching practices. Teaching effectiveness is operationally defined as multiple dimensions of teaching practices observed in inclusive classrooms. This paper examines previously reported and newly completed studies that investigate the characteristics of teachers in inclusive classroom settings, what they believe about their roles and responsibilities and about their students' learning, and how their beliefs relate to their teaching effectiveness with students both with and without disabilities. (Contains 6 tables.)