From 1995 to 2001, the U.S. Department of Labor and the Ford Foundation ran a demonstration of the Quantum Opportunity Program (QOP), mainly an after-school program that also began offering intensive and comprehensive services to at-risk youth when they entered ninth grade. QOP’s goals were to increase rates of high school graduation and enrollment in postsecondary education or training; secondary goals included improving high school grades and achievement test scores and reducing risky behaviors, such as substance abuse, crime, and teen parenting. This final report from Mathematica's random assignment evaluation presents impacts on outcomes measured when most sample members were 22 to 25 years old. Overall, QOP did not achieve its primary or secondary objectives, but the lack of overall impacts masks some suggestive evidence of promising effects for some sites and subgroups.