Personality disorder can be traced back at least to adolescence. Previous research indicates that personality disorder found in adolescents is often linked to personality disorder when they become adults. The DSM defines personality disorders as having their origins in adolescents (APA, 1994). However, there are few studies of adolescent personality disorder, so our understanding of it is limited. The 478-item, true-false format Minnesota Multiphasic Personality Inventory-Adolescent version (MMPI-A; Butcher et al., 1992) was developed for use with adolescents to assess personality relevant to clinical conditions. The 390-item, true-false format Schedule for Nonadaptive and Adaptive Personality-Youth version (SNAP-Y; Linde, 2001) was designed to assess traits using a dimensional approach to personality disorder with adolescents. Relations between these two instruments' scales have been investigated only in the SNAP-Y normative sample. The purpose of this study is to examine relations between the MMPI-A and the SNAP-Y scales, and to investigate scale differences due to age and gender in a clinical sample. Data previously collected on approximately 108 patients who took the MMPI-A and the SNAP-Y as part of the routine intake battery at the Seashore Clinic at the University of Iowa was used for this study. Findings included several correlations between negative temperament and age. Older adolescents were lower in Mistrust, lower in Aggression, and lower in Eccentric Perceptions. Girls scored higher on Hypochondriasis, Depression and Psychasthenia than boys. MMPI-A and SNAP-Y were related on several scales.