Nearly 30 years ago, Math Corps--a summer camp for middle school students in Detroit who could benefit from mentoring and positive influences--was started at Wayne State University (WSU). In 2015, the National Science Foundation awarded an Advancing Informal Science, Technology, Education, and Mathematics (STEM) Learning grant to WSU. As part of the grant, Mathematica conducted an independent study of Math Corps using a quasi-experimental retrospective analysis focusing on long-term outcomes for students who attended Math Corps from 2004 to 2009. This brief presents the results of those analyses, which provide rigorous evidence of the impact of the Math Corps summer program on college enrollment, degree completion, and encounters with the criminal justice system.