Established more than 30 years ago, Career Academies have become a widely used high school reform initiative that aims to keep students engaged in school and prepare them for successful transitions to postsecondary education and employment. Typically serving between 150 and 200 students from grades 9 or 10 through grade 12, Career Academies are organized as small learning communities, combine academic and technical curricula around a career theme, and establish partnerships with local employers to provide work-based learning opportunities. There are estimated to be more than 2,500 Career Academies operating around the country. Since 1993, MDRC has been conducting a rigorous evaluation of the Career Academy approach that uses a random assignment research design in a diverse group of nine high schools across the United States. Located in medium- and large-sized school districts, the schools confront many of the educational challenges found in low-income urban settings. The participating Career Academies were able to implement and sustain the core features of the approach, and they served a cross-section of the student populations in their host schools. This report describes how Career Academies influenced students' labor market prospects and postsecondary educational attainment in the eight years following their expected graduation. The results are based on the experiences of more than 1,400 young people, approximately 85 percent of whom are Hispanic or African-American. The findings demonstrate the feasibility of improving labor market preparation and successful school-to-work transitions without compromising academic goals and preparation for college. Investments in career-related experiences during high school can produce substantial and sustained improvements in the labor market prospects and transitions to adulthood of youth. In fact, Career Academies are one of the few youth-focused interventions that have been found to improve the labor market prospects of young men. At the same time, Career Academies have proven to be challenging to implement on a large scale with high levels of fidelity, and the evidence from this evaluation may not apply to programs that are partially implemented or that use only selected features of the Academy approach. [This report was written with Cynthia J. Willner. An additional funder to the report is the Citigroup Foundation. For the technical resources, see ED631372.]