We examined the predictive utility of the Behavior Assessment System for Children-2 Behavioral and Emotional Screening System (BASC-2-BESS) and Strengths and Difficulties Questionnaire (SDQ) in identifying students with a mental disorder. Data were collected in a two-stage study over 34 months with kindergarten-12th grade (K-12) students (aged 5-19 years) in four US school districts. In Stage 1, teachers completed the BASC-2-BESS and the SDQ. In Stage 2, parents of 1054 children completed a structured diagnostic interview to determine presence of a mental disorder. Results suggest that teacher versions of the BASC-2-BESS and SDQ have modest utility in identifying children meeting criteria for a mental disorder based on parent report. Area under the curve (AUC) statistics representing prediction of any externalizing disorder (0.73 for both measures) were higher than the AUCs predicting any internalizing disorder (0.58 for both measures). Findings can inform the use of teacher report in mental health screening, specifically the selection of measures when implementing screening procedures.