Abstract: Several recent studies using factor analytic methods find that the structure of psychopathology reflects broad internalizing and externalizing dimensions, with the internalizing dimension being further divided into fear and distress disorders. Although these variable-centered studies have provided important insights into the structure of psychopathology, they provide limited information about the classification of individual cases. The present study examines patterns of lifetime internalizing and externalizing psychopathology in participants from the Oregon Adolescent Depression Project using latent class analysis that classifies individuals rather than variables. A 4-class solution best fits the data. The largest class (62.5%) included individuals with relatively little psychopathology; 1 class (16.4%) was largely characterized by internalizing disorders, 1 class (16.9%), largely characterized by externalizing disorders; and the final class (4.2%), characterized by both internalizing and externalizing disorders. The validity of the classes was further examined using data on psychiatric morbidity, temperament, and family aggregation of psychopathology. Classes differed on indices of positive, negative, and disinhibited temperament in ways that were consistent with theoretical predictions. Patterns of familial aggregation of psychopathology demonstrated relative specificity of transmission of different disorders. Overall, the findings support conclusions from studies of dimensional models of internalizing and externalizing disorders, and extend them to person-centered approaches to classification.