In today's technological and global society, STEM disciplines are viewed as fundamental to the nation's economic growth and prosperity. Employment opportunities in STEM fields have increased at a faster rate than in non-STEM fields (Government Accounting Office [GAO], 2006). Additionally, many professions--once perceived not to require STEM skills--are increasingly requiring scientific and technological proficiency (PCAST, 2010). As American students continue to underperform in math and science compared to their peers internationally, concerns have arisen about America's economic and technological competitiveness. Such trends have sparked political interest in uncovering means to more effectively prepare and engage students in these fields. Accelerating greater interest, competence and achievement in STEM fields requires thoughtful analysis of existing research to parse out what is already known about effective strategies for such acceleration, and to highlight where additional research may be warranted. Research on youth development may offer important and applicable lessons about how to most effectively engage students. The research base about youth development provides useful insights for thinking about how best practices for adolescent engagement could apply to programs designed to spur educational and ultimately career interests in STEM. This project focuses specifically on projects that engage STEM-trained adults to work directly with students and identify areas where future research could advance knowledge in the field. By focusing on programs that connect students and adults specifically on STEM content and careers, researchers can begin to dissect the possible benefits of such programs, both in relation to the mission of promoting interest in STEM fields, as well as supporting adolescents' developmental well-being. Several themes emerged from the literature search and from the research findings of the 29 papers in this review. First, the search generated numerous articles on STEM experts working with K-12 students. Another theme is that the focus of research varied widely in terms of the levels of detail provided on STEM professionals' roles and importance in program activities. Some articles highlight the roles played by STEM exerts, and explicitly identify them as a key part of the educational approach of the programs studied. Other articles mention STEM expert involvement in program activities in passing, without describing the nature of adults' involvement, how the experts fit into the larger educational approaches used by the programs, or how the experts are recruited, trained, supported, or reviewed.