Media literacy education is being explored by scholars in many different fields (including education, literature, media studies, psychology, and public health), but there is less evidence of implementations occurring in K-12 settings. With more than 1.3 million teachers in U.S. public schools, it is impossible to estimate the extent to which the instructional practices described in this chapter are widespread or rare. Given the pressures on educators generated by state testing, differential access to technology, and other significant obstacles, it is reasonable to assume that only a small proportion of American students receive any systematic application of media literacy concepts within the context of subject area instruction. Many factors may lead a teacher to begin incorporating media analysis and media production activities into the curriculum. The differences in motivations lie at the heart of some of the arguments and debates that have characterized the media literacy movement's growth and development in the 1990s. Is the diversity of perspectives now in place among content-area practitioners a source of strength and vitality, or has it polarized and paralyzed the development of the field? To address this question, this chapter reviews ongoing educational initiatives in media literacy documented in the emerging body of case study and practitioner literature and identifies those (few) empirical studies that have measured the effects of media literacy instruction on students' knowledge, attitudes, and behaviors, with particular focus on health education, social studies, English language arts, communication arts, and the fine and performing arts. These subject areas have been identified as having the most frequent reference to media literacy in state curriculum documents. From this, recommendations are presented that may help scholars and practitioners to develop this emerging field by exploring questions deserving of further research.