Although there is a strong evidence base for effective substance abuse prevention programs for youths, there is a need to facilitate the implementation and evaluation of these programs in real-world settings. This study evaluates the effectiveness of adapted versions of an evidence-based prevention program, keepin' it REAL (kiR), with alternative school students. Programs are often adapted when used in schools and other community settings, for a variety of reasons. The kiR adaptations, developed during an earlier phase of this study, were created to make the curriculum more appropriate for alternative high school youths. The adaptations were evaluated using a quasi-experimental design in which questionnaires were administered at pretest, posttest, and follow-up, and focus groups were conducted at posttest. Multivariate analyses of variance indicate significantly reduced intentions to accept alcohol and, for younger participants, reduced alcohol use. Focus group data support the need for age-appropriate prevention content. The authors discuss implications for practitioners implementing prevention programs in schools.