This study evaluates whether the psychometric properties of the Pediatric Symptoms Checklist-17 (PSC-17), a common behavioral health measure typically used as a dichotomous screening tool for mental health needs, support its use as a continuous measure for tracking behavioral health over time. A total of 6492 foster parents of children and youth aged 5.5–17 completed the PSC-17. Convergent and discriminant validity was assessed by comparing raw PSC-17 subscale scores with associated outcomes (e.g. psychiatric diagnoses). Long-term test–retest reliability was assessed over 6 months. Scores on the PSC-17 demonstrated good convergent and divergent validity. PSC-17 subscale scores were most strongly associated with analogous diagnoses. Test–retest reliability was moderate, as expected for a time window of this length. This study provides moderate support for the psychometric qualities of the PSC-17 when used with children and youth in the child welfare system as a continuous measure of psychosocial functioning over time