Parental involvement may be a particularly critical component of culturally competent psychotherapy for racial/ethnic minority youth, although limited research in this area is available. The present study aims to address gaps in the literature by 1) examining whether parent cultural variables (race/ethnicity, acculturation, language) predict actual and preferred parental involvement, and 2) investigating whether parent cultural variables and parental involvement predict mental health outcome trajectories and service retention. The sample consists of 264 adolescents (aged 12-19) who have received outpatient mental health services, their parents, and their therapists. Research instruments measure parent cultural variables, preferred and actual parental involvement, functional impairment, symptomatology, and premature termination from baseline to 6-month follow-up time points. Analyses using multi-level modeling were conducted to control for nested data and clustering effects at the therapist level. Overall, hypotheses were supported such that both preferred and actual parental involvement led to a reduction of youth functional impairment. Racial/ethnic minority parents (African American and Hispanic) had higher levels of preferred involvement than non-Hispanic White parents. However, in some instances, Hispanic parents reported less actual involvement. Hispanic parents also reported a significant reduction in their child's functional impairment over time compared to other racial/ethnic groups. Findings from this study may facilitate the development of interventions that encourage parents to play a key role in their child's mental health treatment and improve the quality of care for racial/ethnic minority youth.