Psychiatric disorders are understood to occur as a result of a specific pathology in the brain. Yet ultimately, the diagnosis is made primarily through diagnostic interviews. There are currently no single objective biological marker for any psychiatric disorder. Cognitive control refers to processes that allow us to flexibly adapt our behavior according to our internal goals and external environmental demand. Such processes afford us the capacity to control our thoughts, feelings, and actions. The failure of cognitive control processes in the brain is widely believed to underlie many psychiatric disorders. The aim of this module is to discuss the breakdown of cognitive control in different psychiatric disorders such as OCD, ADHD, schizophrenia and addiction. We will also discuss how different types of treatment such as neuropharmacology and deep-brain stimulation are hypothesised to benefit psychiatric patients through restoring control.