Book excerpt: This book by Judith Langer—internationally known scholar in literacy learning—examines how people gain knowledge and become academically literate in the core subjects of English, mathematics, science, and social studies/history. Based on extensive research, it offers a new framework for conceptualizing knowledge development (rather than information collection), and explores how one becomes literate in ways that mark "knowing" in a field. Langer identifies key principles for practice and demonstrates how the framework and the principles together can undergird highly successful instruction across the curriculum. With many examples from middle and high schools, this resource will help educators to plan and implement engaging, exciting, and academically successful programs.