Teachers are under scrutiny in ways that are unprecedented in recent history. With the spotlight on teacher quality and a focus on the measurement of teaching effectiveness (MET Project, 2010), teachers are expected to excel in inﬂ uencing student achievement even as economic pressures, education policy changes, and technology’s increasing dominance of social interactions alter the educational landscape. The beliefs teachers hold about their capabilities to face these challenges, that is, their self-efﬁ cacy, play a critical role in their motivation to positively inﬂ uence student learning. In light of recent ﬁ ndings that teachers make a more important contribution to student achievement than almost any other social or demographic factor (Staiger & Rockoff, 2010), understanding the motivational beliefs that drive teacher engagement and effectiveness is more important than ever before. This chapter examines teachers’ self-efﬁ cacy beliefs-beliefs about the individual and collective capability to effect change in student learning-from the construct’s beginnings in the United States almost 40 years ago, to the most recent research conducted in a wide range of international settings. Our aim is to explore how theory and research in teachers’ self-efﬁ cacy can be used to inform critical areas of educational policy and practice.