This project report presents numerous definitions of what comprises a prison gang and the need for a universal definition. California's oldest and largest prison gang is the Mexican Mafia. The literature review explains the establishment of the Mexican Mafia in California and Texas. Many inmates join the Mexican Mafia for protection, monetary gain, and a surrogate family. Once these inmates join, they are forced to participate in illegal activities, such as drug trafficking, loan sharking, prostitution, and extortion. The Mexican Mafia has also reached beyond the prison walls into local communities. They control street gang activity, particularly drug trafficking, and require street gangs to pay a tax on their trafficking. The Mexican Mafia has built a violent and dangerous reputation. They use intimidation tactics to control inmates, street gangs, and even family members. This report concludes by presenting ideas to expand strategies that are already in place by law enforcement. The report also makes suggestions for future research to help control prison gangs, both inside the prison and in the community.