The Severity Indices of Personality Problems (SIPP-118; Verheul et al., 2008) is a self-report questionnaire focusing on core components of (mal)adaptive personality functioning. The SIPP-118 was developed and validated in an adult population. In adult populations, the 16 facets of the SIPP-118 fit into 5 higher order domains: self-control, identity integration, relational capacities, social concordance, and responsibility. In this study we present the 1st psychometric properties of the SIPP-118 in adolescents. We compared the SIPP-118 scores of a patient and a nonpatient sample of adolescents, and compared personality disordered and non-personality disordered adolescents. In addition, the relationship between scores on the SIPP-118 and other clinical instruments (Symptom Checklist-90-Revised; SCL-90-R; Derogatis, 1975; Dimensional Assessment of Personality Pathology-Basic Personality; DAPP-BQ; Livesley & Jackson, 2002) was investigated. The questionnaires were completed by 378 adolescent patients and 389 adolescents in the community. Facets appeared to be homogeneous, as alpha coefficients ranged from 0.62 to 0.89, indicating moderate to acceptable reliability. Also, more pathological SIPP-118 scores were found in the patient sample, and more specifically in the personality disordered sample, suggesting that the facet scores of the SIPP-118 can discriminate between various populations (divergent validity). Correlation with other clinical instruments was moderate to high (-0.82 to 0.10). Taken together, the SIPP-118 seems to be a promising instrument measuring personality pathology in adolescents. (Contains 1 figure and 8 tables.)