Various forms of evidence suggest that eating disorders display a special co-aggregation with borderline personality disorder (BPD). In this article, the authors review findings suggesting an apparent affinity between BPD and bulimia. The authors then discuss the implication of BPD on the symptomatic expression and response to treatment of eating disorders. Finally, they explore heuristic dimensions that may explain the specific association of BPD with eating disorders. A discussion follows proposing researchable hypotheses that may permit a better differentiation of processes contributing to the evolution of eating disorders and BPD.