OBJECTIVE: To examine the psychometric properties of the 30-item teacher's version of the Child and Adolescent Symptom Inventory Progress Monitor (CASI-PM-T), a DSM-IV-referenced rating scale for monitoring change in ADHD and co-occurring symptoms in youths receiving behavioral or pharmacological interventions. METHOD: Three separate studies were conducted to determine (a) which items from longer diagnostic instruments were most representative of ADHD and commonly occurring psychiatric syndromes in clinic-referred samples ( N = 406) aged between 3 and 18 years, (b) the reliability and validity of the CASI-PM-T in students enrolled in full-time special education programs at the elementary and middle school levels (N = 169), and (c) the clinical utility of measuring behavioral change in a sample of outpatient ADHD children beginning treatment with stimulant medication. RESULTS: Internal consistency reliabilities (.71-.94), 2-week test-retest reliabilities (r = .70-.90), and interrater agreement (r = .44-.78) for the CASI-PM-T symptom categories were comparable to the full-length CASI-4. Convergence was also found between corresponding CASI-PM-T categories and consultant diagnoses of ADHD and ODD as well as school functioning measures of grade-point average and suspensions. The CASI-PM-T also demonstrated sensitivity to stimulant medication treatment effects. CONCLUSION: Findings provide preliminary support for the reliability, validity, and clinical utility of the CASI-PM-T.