Background: Emerging research has suggested that hoarding may be associated with reduced social cognition, specifically reduced theory of mind and hostility biases, which may contribute to the social difficulties observed in this population. The primary aim of this study was to evaluate the feasibility and acceptability of Social Cognition and Interaction Training (SCIT) in a sample of individuals with Hoarding Disorder (HD) and assess its potential as an adjunct to CBT. We secondarily examined changes in loneliness and hoarding symptoms. Methods: Twelve individuals, with a primary diagnosis of HD, completed a 12-week SCIT program and one booster session. Participants were assessed at pre-treatment, mid-treatment, post-treatment, and one-month follow-up on measures of theory of mind, attributional style, hoarding symptom severity, and loneliness. Results: From pre-to post-treatment, participants had an improvement in theory of mind for sarcastic remarks and a reduction in hostility bias, hoarding symptoms, and loneliness. Retention was also good as all participants completed treatment. Conclusion: These preliminary results suggest that SCIT is a promising treatment to improving social cognition for hoarding disorder and may improve interpersonal difficulties such as loneliness. We propose that SCIT may represent a potential adjunct targeting social factors to improve the efficacy of CBT.