Hoarding has traditionally been linked with OCD and regarded as one of its subtypes. However as of May 2013 hoarding will be included as a new stand-alone diagnosis, named Hoarding Disorder, in the DSM 5. Hoarding has mainly been considered a problem of old age but it also occurs in young people. Our research interest is in the etiology and clinical presentation of hoarding during adolescence. More specifically, we study the heritability of Hoarding Disorder and its etiological link to other disorders by using twin methodology. To this end, we collaborate with the Swedish Twin Registry and the research group of Paul Lichtenstein and David Mataix-Cols from King’s College, London. Volen Ivanov is the primary researcher working on these projects.