Obsessive-compulsive and related disorders (OCRDs) are typically characterized by the [Page 2334]profiles and nosology of adulthood disorders; however, there are a number of developmental considerations and differences that influence the prevalence, clinical presentation, and treatment of these disorders in childhood, adolescence, and older age. Although there is an existing evidence base for empirically supported treatments for most OCRDs, the format and content of these treatments need to be tailored across the age span. This entry summarizes lifespan issues relating to differences in the prevalence and clinical presentation of OCRDs, along with the relevant treatment considerations, with a particular focus on obsessive-compulsive disorder (OCD), hoarding disorder, body dysmorphic disorder (BDD), trichotillomania and excoriation, and tic disorders, including Tourette’s disorder (TD). Given other entries characterizing these disorders ...