This chapter provides an outline of basic cognitive processes and the brain systems that mediate them. For each core process, examples are presented of psychiatric conditions that involve disruption of that process together with a brief consideration of treatment implications. The integration of cognitive with emotional processes is emphasized throughout the chapter. Cognitive control efforts can be hijacked by emotion and, through executive processes, emotion can be enhanced or diminished. The study of working memory and executive function has explored how the brain transforms goals into adaptive deployment of attention, memory encoding, and inhibition of nonrelevant stimuli. These processes are highly relevant to many psychiatric disorders, which often include failures to inhibit irrelevant thoughts and percepts, or difficulties staying “on task.” Combining rigorous measures of behavior and brain parameters with genetic data will be the road towards “precision medicine” in psychiatry.