The authors' purpose was to evaluate the multiple-gate Preschool Behavior Screening System (PBSS) for identifying children's social, emotional, and behavioral (SEB) difficulties. The sample included 122 triads of preschool children between 3 and 5 years old and their parents and teachers. The teacher and parent samples were predominantly women and European American with a substantial African American representation. The design involved numerous indicators of the reliability of scores and the validity of ensuing inferences. Scores from the Behavior Assessment System for Children, Second Edition were used as criterion measures for scores from the PBSS. The PBSS scores were found reliable across scales with Cronbach's alpha values ranging from 0.85 to 0.97. Agreement between teachers and parents was consistent with findings from previous research. Analyzed within a Multitrait-Multimethod Matrix, correlational evidence supported inferences about externalizing difficulties, prosocial behavior, and total problems, as well as internalizing difficulties to a lesser degree. Receiver-operating characteristic curve analyses supported the PBSS across a range of scales and cut scores. Findings support the use of the PBSS as one method for identifying preschool children who may be at risk for SEB difficulties and underscore the importance of using multiple informants in the assessment of SEB difficulties.