Although pathological object relations is a core aspect of borderline psychopathology, few studies have examined borderline object relations empirically, and none has focused on borderline adolescents. The present study examined four dimensions of object relations, as measured by the Thematic Apperception Test, in a sample of adolescent borderlines, psychiatric comparison subjects, and normals. These dimensions are complexity of object representations, affect-tone of relationship paradigms, capacity for emotional investment in relationships and moral standards, and understanding of social causality. Borderlines differed significantly from both comparison groups in several distinct ways, supporting some aspects of psychoanalytic theories of borderline object relations, while challenging others. Borderline adolescents have a malevolent object world, a relative incapacity to invest in others in a non-need-gratifying way, and a tendency to attribute motivation to others in simple, illogical, and idiosyncratic ways. Their object representations, however, can be quite complex, suggesting something other than a preoedipal arrest.