This chapter explores the neurobiological transition from goal-directed behaviors to rigid, maladaptive habits, focusing on the compulsive nature of various psychiatric conditions. It begins by establishing the fundamental differences between flexible, intentional actions and automatic, habitual responses. The discussion then examines key disorders characterized by maladaptive habits, including obsessive–compulsive disorder (OCD), autism spectrum disorder (ASD), and addiction. Most of this chapter delves into the specialized neurocircuitry underlying these conditions. This includes discussion of how dysfunction of the dorsal striatum and the mesocorticolimbic pathway contributes to compulsive behaviors. Emphasis is also placed on how limbic structures, specifically the amygdala and the anterior cingulate cortex (ACC), and the ventral pallidum (VP) promote maladaptive habitual behaviors.