Psychological perspectives and theories on criminal behavior are numerous and distinct. They include, but are not limited to, biological, neurological, cognitive, developmental, personality, and integrated approaches. The purpose of this entry is to offer a brief summary of how these diverse perspectives can provide an understanding of criminal behavior. Although psychological perspectives are less represented within mainstream criminology than other approaches, many criminological theories have a psychological component. Moreover, criminological inquiry can be supplemented and improved by the inclusion of psychological perspectives.