Child maltreatment is a major social welfare problem that creates a highly stressful environment during an important developmental period. The literature on wider issues of stress has been based on a Western stress and coping paradigm, and relatively little is known about the impact of culture in stress and coping processes. The present study examined cultural and ethnic group differences in non-parental social support and coping to identify factors involved in stress and coping mechanisms and their association to internalizing/externalizing symptoms in maltreated adolescents. Participants (n = 219; 52.8% girls) were from the Southwestern site of the Longitudinal Studies of Child Abuse and Neglect (LONGSCAN). The current analyses were limited to White, African American, and Latino participants who completed the age 18 interview. Cultural group was operationalized as ethnic groups, with Whites as belonging to an individualistic and African Americans and Latinos to collectivistic cultures. Non-parental social support was measured by a self-report questionnaire assessing non-parental adult support. The Adolescent Coping Orientation for Problem Experience (A-COPE) measured coping strategies used under stress, and the Youth Self Report (YSR) measured internalizing/externalizing symptoms. One-way ANOVAs were conducted to determine cultural and ethnic group differences in social support and coping. Linear regressions examined the links among social support, coping, and internalizing/externalizing symptoms. Moderation analyses tested the roles of cultural/ethnic groups as moderators of the above relationships. Collectivistic groups were found to utilize significantly more culturally salient coping than the individualistic group, while the African American group utilized significantly more problem-focused and interdependent coping compared to the Latino group. Social support was significantly associated with problemfocused coping, while emotion-focused coping was significantly linked to internalizing/externalizing symptoms. For African American adolescents, problem-focused and culturally salient coping strategies were significantly associated with lower internalizing/externalizing symptoms while an opposite relationship was found for Latino adolescents. The findings provide insight into adolescent coping mechanisms in maltreated youth through a better understanding of the relationships among culture, ethnicity, coping, non-parental social support, and mental health. Based on differences found in coping mechanisms in the current cross-sectional study, future analyses can utilize a longitudinal design to further elucidate these relationships.