Many urban areas experienced an alarming growth of gang activity and violence during the end of the 20th and the beginning of the 21st centuries. Gang members, motivated by various factors, commit a variety of different types of violent acts towards rivals and other targets. The focus of this paper involves instances of displace aggression, which generally refers to situations in which aggression is targeted towards individuals who have either not themselves not committed an offense against the aggressor, or who provide an offense that is too mild to justify the aggression levels that are expressed towards them. It discusses how social-psychological mechanisms and models of two types of displaced aggression might help explain some aspects of the retaliatory behavior that is expressed by members of street gangs. General techniques that have the potential to reduce such aggressive behavior is also proposed. References (Published Abstract)