Extracurricular activities provide a key context for youth development, and participation has been linked with positive developmental outcomes. Using data from the 4-H Study of Positive Youth Development (PYD), this study explored how the intentional self regulation ability of youth interacted with participation in extracurricular activities to affect PYD among adolescents living in neighborhoods with relatively low ecological assets. In total, 545 youth were included in the study (50.3% female). Most of the youth were European American (41%) or Latino (37%; African American, 10%; Asian American, 7%; Native American, 4%; and other, 1%). In general, youth with the greatest capacity to self regulate benefitted the most, as compared to their peers with less capacity to self regulate, from involvement in extracurricular activities. Consistent with a developmental systems perspective, and specifically with bioecological theory, the findings from this study confirmed that, within lower asset settings, children with the most positive person-level factors (intentional self regulation) benefit the most from proximal processes such as extracurricular activity involvement.