This study examines gender, grade-level, and baseline depressive symptoms as potential moderators of a school-based mindfulness intervention's impact on the self-regulatory outcomes of urban youth. Ninety-seven participants from four urban public schools were randomly assigned to an intervention or wait-list control condition. Fourth and fifth graders in the intervention condition received a 12-week yoga-inspired mindfulness program. Using methods outlined by Aiken and West (1991), a series of models estimated the interaction effect of moderators of interest on adjusted posttest self-regulatory outcomes. Results indicate that gender and grade did not moderate intervention impacts. However, baseline depressive symptoms moderated both impulsive action and involuntary engagement stress responses such that intervention youth reporting lower levels of baseline depressive symptoms were more likely to evidence decreases in these problematic stress responses relative to control youth. Findings highlight the need for future studies to examine moderators of mindfulness-based interventions impacts on youth outcomes.