The United States produces the most media--film, television, and music--in the world; yet, media literacy is still a new concept to most Americans, including educators. What media literacy is, why it matters, and how it can be implemented--especially in the schools--constitute the subject of this yearbook. The answers are diverse, as the chapters will show. There is a growing sense of urgency about media literacy in K-college education. Although the definition of media literacy remains contentious, as do different approaches to the field, many scholars, educators, parents, and community activists agree that media literacy is essential in the 21st century. This chapter offers a brief history of the field along with an attempt to define media literacy and offer a rationale for its inclusion in the American public school curriculum. Part I of the yearbook, on the whole, deals with why media literacy can make a difference in American schools. Part II, on the whole, deals with the implementation of media literacy, in and outside the public schools, and the problems facing those who aim to implement it. Media literacy is not without its opponents and its issues. Still, despite differences in theory, focus, and experiences, the contributors to this volume demonstrate their belief in the power of media literacy to transform curriculum, teaching, and even society.