This study was an examination of teachers’ perceptions in two schools: one school that showed exemplary collaboration among its staff and one school that was becoming a more collaborative school. Collaboration is understood as working in cohesion to achieve a common goal (Deal & Peterson, 2009; Fullan & Hargreaves, 1996; Little, 1982; Schlechty, 2009). One focus group with teachers at each school, with follow-up individual interviews, provided the data explaining colleagues’ influences on engagement in professional development. The findings of this study suggest that colleagues have an important effect on teachers’ engagement in professional development. Participants indicated that colleagues were a factor of engagement because they increased engagement through fulfilling their desire for face-to-face instruction, through their appreciation of being worked with, rather than worked on (Morewood & Bean, 2009), and through networking. As teacher participants worked together in professional development, they increased their school’s organizational capacity (Mitchell & Sackney, 2001).