Many patients with substance abuse problems present with co-occurrent cluster C personality disorders. Focusing on both disorders disrupts the maintenance mechanisms and the vicious cycle between the 2 conditions; however, treatment teams often neglect this issue. In this work, we describe the features of metacognitive interpersonal therapy as applied to a man with avoidant and depressive personality disorders and heroin, cocaine, and alcohol abuse. Psychotherapy proceeded through the following steps: (a) conducting drug therapy to deal with symptoms of abstinence from heroin; (b) forming a therapeutic bond to overcome the patient's severe emotional withdrawal; (c) fostering basic metacognitive capacities such as awareness of emotions and their triggers; (d) sharing formulations of maladaptive interpersonal schemas and descriptions of the associated states of mind; (e) conveying an understanding of the link between interpersonal events (recent ones and traumatic memories) and substance abuse; (f) facilitating the acquisition of critical distance from maladaptive schemas; and (g) promoting the use of adaptive coping skills instead of resorting to substance abuse. Implications for generalizing these procedures to the treatment of other patients with co-occurrent personality disorders and substance abuse are described.