Purpose: A signature characteristic of positive youth development (PYD) programs is the opportunity to develop life skills, such as social, behavioral, and moral competencies, that can be generalized to domains beyond the immediate activity. Although context-specific instruments are available to assess developmental outcomes, a measure of life skills transfer would enable evaluation of PYD programs in successfully teaching skills that youth report using in other domains. The purpose of our studies was to develop and validate a measure of perceived life skills transfer, based on data collected with The First Tee, a physical activity-based PYD program. Method: In 3 studies, we conducted a series of steps to provide content and construct validity and internal consistency reliability for the Life Skills Transfer Survey (LSTS), a measure of perceived life skills transfer. Results: Study 1 provided content validity for the LSTS that included 8 life skills and 50 items. Study 2 revealed construct validity (structural validity) through a confirmatory factor analysis and convergent validity by correlating scores on the LSTS with scores on an assessment tool that measures a related construct. Study 3 offered additional construct validity by reassessing youth 1 year later and showing that scores during both time periods were invariant in factor pattern, loadings, and variances and covariances. Studies 2 and 3 demonstrated internal consistency reliability of the LSTS.Conclusion: Results from 3 studies provide evidence of content and construct validity and internal consistency reliability for the LSTS, which can be used in evaluation research with youth development programs.