Over the past decade, "out-of-school time" and "after-school programs" have been identified as objects of research, funding, and policy initiatives across federal and state agencies as well as public, private, and nonprofit foundations. The increasing attention to and funding of programs that engage youth outside of the formal institution of schooling was motivated by a number of overlapping concerns, including a desire to improve school achievement, a commitment to youth safety, and an interest in enrichment programs that offer opportunities to explore and study in the arts or sciences, coupled with occasions for social and emotional development. The field of informal contexts for learning generally reflects a goal of learning "writ large," that is, learning that is not designed in many instances to meet the formal institutional structures and demands of schooling. The focus of this chapter is on "structured" informal contexts that engage young people between 12 and 18 years old in the United States, for example, those found in after-school programs and community-based youth organizations, which represent the bulk of the research in the field. The first section describes the method used to conduct the review. The second section provides a historical perspective for the chapter, along with a discussion of terms and categories and a framework. The third section examines theoretical and methodological issues that have surfaced in the field of learning in informal contexts. Promising programs of research and promising informal programs based on research are highlighted in the fourth section. In the fifth section, social and discursive practices are described, with an emphasis on how contexts for learning are constituted through participation. In the sixth section, gaps in the research and additional questions are coupled in an attempt to identify directions for future research. (Contains 1 table and 3 notes.)