The aim of this study was to gain greater insight into the relationship of delinquency to personality and social competence in incarcerated girls. It was hypothesized that agreeableness and conscientiousness would correlate negatively with delinquency, and that the sensation-seeking aspect of extroversion would correlate positively. Two theoretical views were used to predict the relationship between social competence and delinquency: (a) delinquency as an expression of lack of social competence (i.e., social deficit), and (b) delinquency as socially competent and rationally analyzed behavior. The first view implies a negative correlation between delinquency and social competence, while the second indicates a positive one. The participants were thirty-three 12- to 18-year-old incarcerated girls. An adaptation of the Self-Reported Delinquency Scale was used for measuring delinquency; personality was measured using the Five-Factor Personality Inventory; and the Scale for Interpersonal Behavior was used to measure social competence. Agreeableness was not found to correlate with the overall delinquency score or with any specific type of delinquency or crime. The more crimes the girls reported, the less conscientious they were, and the more neurotic and open they were. The correlation between delinquency and extroversion was not statistically significant. A higher level of delinquency was accompanied by higher social competence when negative self-assertion was required (i.e., a low level of tension was felt in expressing negative feelings that were appropriate to the situation). In other social situations, however, the girls reported more situation-inappropriate feelings of tension. It was concluded that some personality factors and aspects of social competence can predict delinquency.