Cognitive behavioral therapy (CBT) for hoarding disorder (HD) has resulted in statistically significant improvements in hoarding symptoms, but gains have been modest and most participants continue to have clinically significant symptoms at post treatment. Contingency management, an empirically-supported intervention for substance use, may be effective in overcoming barriers to effective treatment of HD, such as fluctuating motivation and insight. The objective of the current open trial was to examine the potential effectiveness of contingency management for HD in the context of a cognitive-behavioral group therapy. Twenty-two patients completing 16-week CBT groups for HD were administered monthly contingency payments based on independent evaluator-rated reductions in overall in-home clutter. Mixed effects models suggested significant reductions in hoarding symptoms as measured by the Saving Inventory-Revised (SI-R; Frost, Steketee, & Grisham, 2004) and the Clutter Image Rating Scale (CIR; Frost, Steketee, Tolin, & Renaud, 2008), with SI-R reductions resulting in a large effect size (Cohen's d =2.59) that surpassed those obtained previously in trials of CBT for HD. Mean total earning per patient was $139, and ranged from $0 to $270. These preliminary results suggest that contingency management shows promise as a cost-efficient adjunctive intervention to boost gains in CBT for HD.