This book presents a comprehensive overview of the epistemological underpinnings of a sociocultural perspective on human learning and addresses in detail what this perspective has to offer the field of second language teacher education. Captured through five changing points of view, it argues that a sociocultural perspective on human learning changes the way we think about how teachers learn to teach, how teachers think about language, how teachers teach second languages, the broader social, cultural, and historical macro-structures that are ever present and ever changing in the second language teaching profession, and what constitutes second language teacher professional development. Overall, it clearly and accessibly makes the case that a sociocultural perspective on human learning reorients how the field understands and supports the professional development of second language teachers.