Drawing on qualitative case study research in four small schools, this paper explores the relationship between the professional contexts of schools--specifically supports for: (1) collaboration focused on improving instruction; (2) professional development and teacher learning opportunities; and (3) the degree to which teachers have authority and leadership in shaping curriculum and school practice--and teachers' delivery of high-quality instruction. Looking across multiple sources of data from four schools, we found clear differences in terms of the extent to which we saw teacher collaboration with a culture of reflection and inquiry, professional development aligned with teachers' emergent needs, and shared leadership that encourages teacher authority.