This study examines the psychometric properties of the Therapeutic Alliance Scale for Caregivers and Parents (TASCP) in a sample of 209 caregivers whose children (ages 4–13) presented with disruptive behavior problems to publicly funded outpatient mental health clinics in San Diego County. Information about therapeutic alliance was collected from children, caregivers, and their therapists across the course of therapy (up to 16 months). Results supported the reliability, temporal stability, convergent validity, and discriminant validity of scores on the TASCP. The multilevel factor structure of this new measure was consistent with the parallel child-report version, with two within-level factors and one between-level factor. Furthermore, predictive validity was strong, with stronger caregiver-reported alliance associated with more sessions attended, greater satisfaction with perceived improvement, and less drop-out.