In-home Decluttering Augmentation of Group CBT for HD

Inclusion Criteria: 1. Age 18 years or older. 2. Hoarding disorder as primary psychiatric condition. 3. Willing and able to understand and complete consent and study procedures. 4. Living in the Stockholm county (Sweden) and within a 1-hour commute by public transport from the social services office. Exclusion Criteria: 1. Concurrent CBT or having received CBT for HD during the last two years, for a minimum of 8 sessions including active strategies for reducing acquisition and practice of discarding with a qualified therapist or 8 previous in-home decluttering sessions with a qualified social worker. 2. Unable or unwilling to allow study staff into home for home assessment. 3. Animal hoarding or squalid (i.e. extremely unhygienic) home conditions that are deemed to put the personnel at risk during the in-home decluttering. 4. A diagnosis of organic brain disorder, intellectual disability, psychosis, bipolar disorder without stable medication or with symptoms within the last 6 months, anorexia nervosa or alcohol/substance dependence or abuse. 5. Major medical or neurological conditions that increase the risk of participation or that would prevent completing assigned behavioral practice tasks. 6. Immediate risk to self or others, requiring urgent medical attention, such as high suicidality risk. 7. Participant not able to read and communicate in Swedish. 8. Currently at high risk for eviction (for instance having received a "rättelseanmaning" by the housing company or Swedish court). 9. Potential participant lives in the same household as an already included participant.