Current middle-school standards require students to operate at levels of literacy never before expected of 10- to 14-year-olds. This monograph, written for teachers, addresses literacy development in middle-school students, stressing the crucial role of teachers. It suggests that teachers must change the core of educational practice and examine their ideas about knowledge, the role of students and teachers in the educational process, and how their ideas or beliefs about learning are translated into instructional practice. The first chapter, "The Best of Times and the Worst of Times: Early Adolescence in the 21st Century," discusses biological, physical, cognitive, social, and emotional changes that occur during the ages between 10 and 14. The second chapter, "New Learning Paradigms for a New Millennium," provides an overview of learning theories that influence classroom practice, including behavioral theory and cognitive theory. The third chapter, "Creating Optimal Literacy Environments for Young Adolescents," examines how three principles of learning-construction of meaning, active engagement, and meaningful content-can be used to visualize literacy environments for middle-school students that maximize reading and writing achievement. Appendix I, "Suggested Professional Books," and Appendix II, "Suggested Authors and Their Works," are annotated bibliographies. (Contains 100 references.) (WFA)