The Multidimensional Personality Questionnaire (MPQ) is a widely used personality assessment instrument informing lower- and higher-order personality dimensions. Despite recent developments of brief (MPQ-BF) and simplified wording (MPQ-SF) forms, there is relatively little work on the utility and validity of the MPQ in younger samples with lower reading levels. This study is the first to assess the reliability, factor structure, and criterion validity of the MPQ-SF in a sample of treatment-referred mid-adolescents (N = 105; 12-17 years). Results suggest adequate reliabilities for most of the lower-order primary scales and support a three-factor structure of the MPQ-SF, consistent with previous research with adult and college-aged samples. However, there were also notable cross-loadings for particular scales, which we discuss in relation to the four-factor MPQ model and the Five Factor Model of Personality. Relationships between MPQ personality dimensions and psychopathology using youth, parent, and clinician-rated psychopathology indices supported criterion-related validity. Together, these results confirm the utility of the MPQ in youth with treatment histories.