Organized activity participation is associated with a wide array of positive developmental outcomes. Latinos are one of the largest and fastest growing ethnic groups in the U.S., yet are less likely to participate in organized activities than their peers. Theoretically, the alignment or fit between adolescents' and their activities' characteristics is critical to support youths' use and engagement in organized activities. Using qualitative data in Study 1, I examined parents' and adolescents' perspectives and experiences related to several indicators of ethnicity and culture in their activities. Results suggested that alignment on Spanish-language use was critical for participation. However, some Latino families did not prefer aspects of ethnicity and culture in their activities because adolescents learned about their culture with family or because adolescents wanted to fit in with their majority White peers. Study 2 tested quantitatively whether features of ethnicity and culture in the activity mattered for Latino adolescents' experiences during activities. Ethnic and cultural features in activities, particularly respect for one's ethnicity and culture, fostered positive experiences during activities. Unexpectedly, some ethnic and cultural features were detrimental, such that overt teaching about ethnicity and culture was related to negative feelings during the activity. There was little evidence that the relation between ethnic and cultural features in activities and concurrent experiences varied by Latino cultural orientation. Integrating the findings across these two studies, there was mixed evidence for the traditional theoretical notions that optimal development occurs in environments that fit with individual's characteristics. Complementary fit was optimal when adolescents' needs were considered across the many contexts in which their lives are embedded, including their families and neighborhoods. I recommend that practitioners should take care in learning about the specific families and youth that their activity serves to best understand how to meet their needs. Some aspects of culture, such as Spanish-language use may be critical for participation; other aspects may require special attention from activity leaders, such as teaching about ethnicity and culture. This dissertation is an important step in understanding how to best design activities that promote the recruitment and retention of Latino youth in organized activities.

Previous research suggests that the relation between sport participation and alcohol use is positive, but small in size. Few explanations for this positive relation have been empirically tested. Theories denote that the relation between sport participation and alcohol use is explained by peers and that the relation varies based on the models adolescents are exposed to. This study tested mediators (popularity and friends' alcohol use) and moderators (sport-focus, teammates' alcohol use, gender, popularity, and friends' alcohol use) for the relation between sport participation and alcohol use. Analyses were conducted through path models in Mplus v5.1. The sample included 48,390 adolescents (mean age=15.8 years; 51% female) from the National Longitudinal Study of Adolescent Health. In the self-administered in-school questionnaire, adolescents reported on their activity participation, alcohol use, friendship nominations, and demographic characteristics. Friend indicators were based on friends' self-reported alcohol use. Results suggested that popularity mediated, but did not moderate the relation between sport participation and alcohol use. In contrast, friends' alcohol use moderated, but did not mediate this relation. The relation was positive and strongest for sport-focused adolescents, and for adolescents whose teammates and sport friends used high levels of alcohol. The findings of this study suggest athletes are at an elevated risk for alcohol use, but not all athletes drink. Peers are important predictors, such that, sport participation may be related to alcohol use, partially, because it promotes adolescents' social status. The sport context is also important, such that, athletes are more likely to use alcohol if they are highly involved in sports, and they have sport friends and teammates who drink. Specific types of athletes, such as popular athletes, should be targeted for alcohol use interventions. Intervention programs should also be designed to capture specific aspects of the sport context, such as teams without no tolerance substance use policies, and highly competitive or stressful sports.