Court-involved youth (CIY) comprise a significant portion of the U.S. population and have a high prevalence of psychiatric illness and substance use. Youth delinquency has also been associated with family variables and parenting practices. However, it is not known which family factors are most relevant to behavioral outcomes in CIY mandated to outpatient mental health treatment. Self-report measures from 163 CIY (M = 15.19 years; 58.3% male) starting psychiatric care in two U.S. cities were utilized in a cross-sectional analysis to examine the association of parental monitoring and family functioning with the severity and variety of delinquent acts. Results demonstrate that parental monitoring is significantly associated with the delinquent behavior of CIY in mental health treatment, beyond that of psychiatric symptoms and substance use. Improved understanding of influential family factors can enhance tailoring of existing interventions to ensure that they are relevant to the needs of CIY, especially those in psychiatric treatment.