In an attempt to understand why human beings aggress, this article briefly overviews conceptualizations of anger and aggression and presents a structured and time-limited group-treatment approach to aggression and violence. The treatment was offered five times in a group setting to a total of 51 inmates in a correctional institute. An evaluative study employing a pre- and posttreatment design indicated significant reduction in susceptibility to anger, a decrease in aggressive tendencies, and an overall significant increase in appropriate social behavior. (PsycINFO Database Record (c) 2016 APA, all rights reserved)