This cross-sectional study examined why Latinx adolescents participated in organized activities in comparison to White adolescents. This study, utilizing phone interviews for surveying, included 236 participants (53% female) of Latinx (64%) and White (36%) descent from four Southwest middle schools to answer these overarching questions: (1) What are the dimensions of adolescents' reasons for participating in activities and how do these reasons differ across White and Latinx adolescents? (2) How are cultural orientations (i.e., enculturation and acculturation) associated with dimensions of reasons behind activity participation, and how are dimensions of reasons linked to engagement and activity experiences among Latinx adolescents? Results showed that Latinx adolescents endorsed more family/achievement-oriented reasons than White adolescents. Among Latinx adolescents, high acculturation was associated with high endorsement of individual-oriented reasons. High enculturation was associated with both high endorsement of family/achievement-oriented and individual-oriented reasons. In addition, individual-oriented reasons, family-oriented reasons, and social-oriented reasons all predicted positive engagement and peer support in the activity. Yet, only individual-oriented reasons predicted positive leader support.