Objective: To develop a reliable and valid parent-report screening instrument for mania, based on DSM-IV symptoms. Method: A 21-item Child Mania Rating Scale-Parent version (CMRS-P) was completed by parents of 150 children (42.3% female) ages 10.3 plus or minus 2.9 years (healthy controls = 50; bipolar disorder = 50; attention-deficit/hyperactivity disorder [ADHD] = 50). The Washington University Schedule for Affective Disorders and Schizophrenia was used to determine DSM-IV diagnosis. The Young Mania Rating Scale, Schedule for Affective Disorders and Schizophrenia Mania Rating Scale, Child Behavior Checklist, and Child Depression Inventory were completed to estimate the construct validity of the measure. Results: Exploratory and confirmatory factor analysis of the CMRS-P indicated that the scale was unidimensional. The internal consistency and retest reliability were both 0.96. Convergence of the CMRS-P with the Washington University Schedule for Affective Disorders and Schizophrenia mania module, the Schedule for Affective Disorders and Schizophrenia Mania Rating Scale, and the Young Mania Rating Scale was excellent (0.78-0.83). The scale did not correlate as strongly with the Conners parent-rated ADHD scale, the Child Behavior Checklist-Attention Problems and Aggressive Behavior subscales, or the child self-report Child Depression Inventory (0.29-0.51). Criterion validity was demonstrated in analysis of receiver operating characteristics curves, which showed excellent sensitivity and specificity in differentiating children with mania from either healthy controls or children with ADHD (areas under the curve of 0.91 to 0.96). Conclusion: The CMRS-P is a promising parent-report scale that can be used in screening for pediatric mania. (Contains 2 figures and 4 tables.)