Background: Racial/ethnic-minority 9th graders are at increased risk for teen pregnancy, HIV, and STIs compared to their White peers. Yet, few effective sexual health education programs exist for this population. Purpose: To apply "IM Adapt"--a systematic theory- and evidence-based approach to program adaptation--to modify an effective middle school sexual health education curriculum, "It's Your Game…Keep It Real!" ("IYG"), for racial/ethnic-minority 9th graders. Methods: Following the six steps of "IM Adapt", we conducted a needs assessment to describe the health problems and risk behaviors of the new population; reviewed existing evidence-based programs; assessed the fit of "IYG" for the new population regarding behavioral outcomes, determinants, change methods, delivery, and implementation; modified materials and activities; planned for implementation and evaluation. Results: Needs assessment findings indicated that "IYG" targeted relevant health and risk behaviors for racial/ethnic-minority 9th graders but required additional focus on contraceptive use, dating violence prevention, active consent, and access to healthcare services. Behavioral outcomes and matrices of change objectives for "IYG" were modified accordingly. Theoretical methods and practical applications were identified to address these behavioral outcomes, and new activities developed. Youth provided input on activity modifications. School personnel guided modifications to "IYG"'s scope and sequence, and delivery. The adapted program, "Your Game, Your Life," comprised fifteen 30-minute lessons targeting determinants of sexual behavior and healthy dating relationships. Pilot-test data from 9th graders in two urban high schools indicate promising results. Conclusion: "IM Adapt" provides a systematic theory- and evidence-based approach for adapting existing evidence-based sexual health education curricula for a new population whilst retaining essential elements that made the original program effective. Youth and school personnel input ensured that the adapted program was age-appropriate, culturally sensitive, and responsive to the needs of the new population. "IM Adapt" contributes to the limited literature on systematic approaches to program adaptation.