Tourette Syndrome (TS) and Obsessive-Compulsive Disorder (OCD) are highly associated and often it is difficult to differentiate their symptomatology. In TS, habit forming neuronal systems may form habits of their ownsometimes similar to ritualized behavior. However, whereas in OCD merely the affect-loop is touched, in TS the sensorimotor-loop plays the major role, although some overlap can be seen in the clinical spectrum between TS and OCD. The latter is mainly related to the just-right phenomenon which shows a clear developmental course. An analogous behavioral model for TS and OCD with reference to just-right is suggested.