Obsessive-compulsive disorder (OCD) and related disorders have been the subject of significant revisions in the fifth edition of the Diagnostic and Statistical Manual (DSM-5). One of these major changes has been the removal of OCD from the ‘Anxiety Disorders’ section and its instalment in a new and distinct Obsessive-Compulsive and Related Disorders (OCRDs) chapter. However, it is the instatement of hoarding disorder (HD) as a new OCRD that marks the most significant change. Previously considered a symptom of OCPD, and subsequently linked to OCD, it is now acknowledged that hoarding can emerge independently from any alternative condition. The present paper provides an updated review of recent investigations supporting the status of HD as an independent nosological entity. Specifically, we will present the new DSM-5 diagnostic criteria and examine the literature pertaining to the psychopathological and phenomenological aspects of the disorder, with particular attention to practical strategies that can help clinicians to recognise and differentiate HD from OCD. Finally, the available assessment and treatment strategies for HD are summarised.