Purpose: This study examined the construct validity and reliability of a therapeutic alliance measure (Children's Alliance Questionnaire [CAQ]) for children with psychosocial and/or behavioral problems, receiving therapeutic residential care or day care in the Netherlands. Methods: Confirmatory factor analysis of a one-factor model ''therapeutic alliance'' was conducted on two samples of 115 and 116 children, aged 4-14 years. Reliability analysis and concurrent validity were examined. Results: Results showed a good fit to the data, indicating construct validity of the measures. Cronbach's a reliability coefficients were good for both alliance measures. Concurrent validity was supported by significant relations between the alliance scale and positive group climate (Group Climate Instrument for Children [GCIC]) and treatment motivation (Adolescent Treatment Motivation Questionnaire). No correlations with negative group climate (GCIC) were found. Discussion: The CAQ can be used as an assessment tool for therapeutic alliance within both residential treatment and therapeutic day care settings for children.