© 2014 by Nova Science Publishers, Inc. All rights reserved. Recent decades have witnessed a dramatic shift toward a developmental approach in the study of psychopathology. Two polarities models of personality development have attracted considerable research attention in this context. These models propose that normal personality development is characterized by a dialectic interaction between the development of the capacity for relatedness or attachment, on the one hand, and self-definition or autonomy, on the other. Disruptions of this developmental dialectic are presumed to lead to an excessive emphasis on one or the other of these developmental lines, expressed as high levels of dependency or self-critical perfectionism, respectively. While the value of this theoretical model for understanding the development of internalizing disorders in adolescence has been extensively investigated, fewer studies have focused on externalizing problems. From a theoretical perspective, both dependency and self-critical perfectionism can be expected to be associated with externalizing disorders, and conduct disorde (CD) in particular, through elevated levels of sensitivity to ostracism and to rejection, leading to reactive aggression and associated conduct problems. However, the mechanisms involved are poorly understood. Vulnerable self-esteem, as implied in the concepts of overt and covert narcissism, may explain the relationship between the two personality dimensions and sensitivity to ostracism. This study investigated whether overt and covert narcissism mediate the relationship between dependency, self-critical perfectionism, and sensitivity to ostracism, using a virtual ball-toss game (Cyberball) in a sample of 29 male adolescent offenders with serious CD. Results showed that covert, but not overt, narcissism, mediates the relationship between dependency, self-critical perfectionism, and sensitivity to ostracism. These relationships were particularly strong for dependency. Results suggest that highly dependent and self-critically perfectionistic adolescents with CD may covertly harbor feelings of grandiosity and entitlement, which may make them more vulnerable for sensitivity to ostracism and, ultimately, externalizing behavior. Further research is needed to replicate these findings.