Although organized activities promote positive youth development, Latina/os are least likely to participate among ethnic minority youth. This study tested whether an indicator of social stratification, namely mothers' documentation status (i.e., nativity, citizenship, and legal status), explained low activity participation rates among Mexican and other Latino youth. As a secondary goal, this study tests competing hypotheses about whether the relation between documentation status and participation varied by youth age. Using Los Angeles Family and Neighborhood Survey data, regression results indicated that Latino youth with unauthorized immigrant mothers were significantly less likely to participate in organized activities than those with native-born mothers, controlling for other variables. Post-estimation analyses indicated that participation gaps associated with mothers' documentation status were larger for older than younger Latino youth. These findings suggest that documentation may function on a developmental continuum and that there was a developmental amplification of the effects of parents' documentation status on youth activity participation.AQ3