Obsessive-compulsive disorder is a disorder in which people have recurring, unwanted thoughts, ideas, or sensations (obsessions) that make them feel driven to do something repetitively (compulsions). This chapter contains three cases of obsessive-compulsive and related disorders in three adolescent males. While the clients in each of these cases have symptoms that lead to a DSM-5 (Diagnostic and Statistical Manual of Mental Disorders: Fifth Edition) diagnosis in the same category, this chapter highlights how the disorder often presents in different ways and with different obsessive thoughts (e.g., sexual orientation obsession). Obsessive-compulsive disorder may co-occur with Tic disorder and a case that demonstrates this link is included. Questions for consideration are also included.