The study aim was to test whether a 12‐week publically rebated group programme, based upon Steketee and Frost's Cognitive Behavioural Therapy‐based hoarding treatment, would be efficacious in a community‐based setting. Over a 3‐year period, 77 participants with clinically significant hoarding were recruited into 12 group programmes. All completed treatment; however, as this was a community‐based naturalistic study, only 41 completed the post‐treatment assessment. Treatment included psychoeducation about hoarding, skills training for organization and decision making, direct in‐session exposure to sorting and discarding, and cognitive and behavioural techniques to support out‐of‐session sorting and discarding, and nonacquiring. Self‐report measures used to assess treatment effect were the Savings Inventory—Revised (SI‐R), Savings Cognition Inventory, and the Depression, Anxiety and Stress Scales. Pre‐post analyses indicated that after 12 weeks of treatment, hoarding symptoms as measured on the SI‐R had reduced significantly, with large effect sizes reported in total and across all subscales. Moderate effect sizes were also reported for hoarding‐related beliefs (emotional attachment and responsibility) and depressive symptoms. Of the 41 participants who completed post‐treatment questionnaires, 14 (34%) were conservatively calculated to have clinically significant change, which is considerable given the brevity of the programme judged against the typical length of the disorder. The main limitation of the study was the moderate assessment completion rate, given its naturalistic setting. This study demonstrated that a 12‐week group treatment for hoarding disorders was effective in reducing hoarding and depressive symptoms in an Australian clinical cohort and provides evidence for use of this treatment approach in a community setting. Copyright © 2016 John Wiley & Sons, Ltd. Key Practitioner Message A 12‐week group programme delivered in a community setting was effective for helping with hoarding symptoms with a large effect size. Hoarding beliefs (emotional attachment and responsibility) and depression were reduced, with moderate effect sizes. A third of all participants who completed post‐treatment questionnaires experienced clinically significant change. Suggests that hoarding CBT treatment can be effectively translated into real‐world settings and into a brief 12‐session format, albeit the study had a moderate assessment completion rate.