In 2015-16, the Middle Level Education Research Special Interest Group (MLER SIG), an affiliate of the American Educational Research Association, undertook a collaborative project—the development of a new middle grades education research agenda. The purpose of the MLER SIG Research Agenda (Mertens et al., 2016) was to develop a set of questions that would guide the direction of middle grades education research. Ideally, this Research Agenda would serve to prompt discourse and generate research projects that could contribute to the middle grades knowledge base. Members of the MLER SIG identified eight research areas: (a) young adolescent development, (b) cultural responsiveness, (c) special populations, (d) educator development, (e) curriculum, (f) social and emotional learning, (g) digital technologies, and (h) school structures. This volume contains the extensive literature reviews and subsequent research questions for each of the research topics.