In this review of three dozen methodologically rigorous global studies, Darling-Hammond et al. found that “collective work in trusting environments provides a basis for inquiry and reflection into teachers’ own practices, allowing teachers to take risks, solve problems, and attend to dilemmas in their practice” (p. 10). This article also references the 2014 OECD TALIS study which found that teacher collaboration is positively associated with professional confidence and that “frequent engagement in joint activities across classes and collaborative professional learning are positively associated with teacher self-efficacy and job satisfaction” (p.112). Another observation made by Darling-Hammond et al is that teachers in the US spend about 50% more of their week than the international average in classrooms with students and observed that for other countries “in the time that teachers are not directly engaged with students they are frequently working with each other to plan lessons collaboratively or to conduct action research and analyze their practice and its outcomes” (p.113).