To succeed in a 21st century world, the ability to communicate, innovate, think, problem solve, and collaborate is essential. Citizens in a democracy need skill in using knowledge to make informed judgments in daily life and to consider issues that impact their world. Traditional instruction in high school classrooms is no longer adequate for developing these skills. Current thinking highlights a disciplinary literacy approach in which students gain subject-area knowledge through the discourses characteristic of each subject area. This book describes a study that compares traditional instruction with innovative teaching practice that employs EngageALL—Engagement Model of Academic Literacy for Learning—that supports the gradual expansion of content-area understanding. Findings reveal that improved thinking and learning result when instruction is sequenced with attention to interest development, inquiry, zone of proximal development, positive learning experiences, and sustained engagement with social-constructivist activity that emphasizes the rich academic discourses of the subject-area domain. This book bridges research and theory to classroom practice and professional development.