Multi-informant reports of student emotional and behavioral problems determine eligibility for school-based services; however, multiple informants often yield inconsistent reports of child concerns. Informant discrepancies are thought to reflect either measurement error or meaningful differences (e.g., situational variation). It is important to understand the source of inconsistencies because informant discrepancy may influence treatment outcome. The current study assessed whether informant discrepancies of internalizing and externalizing symptoms reflect meaningful differences between informants. Parents, teachers, and children (N = 169; M age = 10.32; 65.1% Black, 30.8% Latino/Hispanic; 66.9% Male) completed the Behavior Assessment System for Children, 2nd Edition (BASC-2). The Operations Triad Model (OTM) guided the data analysis plan to identify the source of informant discrepancy. We predicted that informant discrepancy would reflect meaningful differences, as opposed to measurement error. Parent-teacher reports of hyperactivity, aggression, and anxiety, as well as teacher-child reports of anxiety and hyperactivity, supported the idea that informant discrepancies of internalizing and externalizing symptoms reflected meaningful differences. Implications of these discrepancies for interpretation of results in school-based assessment of emotional and behavioral disorders are discussed.