Objectives: We developed a comprehensive measure to evaluate 11 domains of maternal social support for physical activity (PA) among Latina adolescents. Methods: The 26-item questionnaire included a version for mothers to rate how often they engaged in behaviors supporting their daughters' PA, and a version for daughters to rate how often their mothers engaged in the same behaviors. Bivariate correlations examined associations between mother-daughter perceived support for daughter's moderate-to-vigorous PA (MVPA), and associations between daughter's perceived support for PA and current MVPA. Results: Twenty-one Latina adolescents, which included 20 adolescent-mother dyads, enrolled in the study. Mother-daughter ratings of support showed significant positive correlations for reminders (r = .573, p = .01), watching daughters' sports (r = .566, p = .01), limit-setting (r = .564, p = .01), encouragement (r = .561, p = .01), transportation (r = .544, p = .02). We found statistically significant associations between MVPA and daughters' ratings of their mothers valuing (r = .544, p = .02) and facilitating PA (r = .48, p = .05). Conclusions: Mothers accurately perceive several supportive behaviors for PA given to daughters, but only daughters' perception of received support predicts their MVPA.