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 own – sometimes 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.