BACKGROUND: Time-limited group cognitive behavioral treatments (GCBT) for obsessive-compulsive disorder have demonstrated improvement in target symptoms. One small sample study of GCBT specifically for hoarding problems also showed benefit. This study examines the efficacy of a specialized GCBT for compulsive hoarding on a larger sample. METHODS: Thirty-two clients diagnosed with hoarding participated in five groups. Four groups met once weekly for 2 hour over 16 weeks (n=27) and one group met for 20 weeks (n=5). All participants had two individual 90-min home sessions. Self-report assessments were completed at baseline, mid-treatment, and post-treatment about hoarding behavior and related symptoms (e.g., depression). The sample was predominantly female, White, highly educated, unemployed, and not partnered/married; mean age was 53. A majority was diagnosed with major depressive disorder and obsessive-compulsive personality disorder. RESULTS: Participants showed significant improvement from pre- to post-treatment on the Saving Inventory Revised, Saving Cognitions Inventory, Clutter Image Rating, and Clinical Global Severity. The most recent group (n=8) that used a more formalized treatment and research protocol improved significantly more than did earlier members. CONCLUSION: This study demonstrates the feasibility and modest success of GCBT methods in improving hoarding symptoms. Group treatment may be especially valuable because of its cost-effectiveness, greater client access to trained clinicians, and reduction in social isolation and stigma linked to this problem. Further research is needed to improve the efficacy of GCBT methods for hoarding and to examine durability of change, predictors of outcomes, and processes that influence change.