The goal of this study was to examine if attachment theory can provide a framework for understanding treatment completion in an eating disorders partial hospital program among women with anorexia nervosa (AN). Attachment was measured using the Attachment Styles Questionnaire (Feeney, Noller, & Hanrahan, 1994). As hypothesized, self-reports of high avoidant attachment predicted noncompletion of treatment for those with AN binge-purge subtype (ANB). However, this relationship did not emerge for those with AN restricting subtype (ANR). Also as hypothesized, self-reports of high anxious attachment predicted completing treatment for those with ANB but not for those with ANR. For completers with ANB and ANR, the program was helpful in increasing body weight and lowering drive for thinness, body dissatisfaction, interpersonal problems, and depression. Attachment avoidance, characterized by devaluing one's need for relationships, may be a contraindication for group-based partial hospital treatment of ANB. Attachment anxiety, characterized by high preoccupation with relationships, may facilitate remaining in treatment for those with ANB.