Barrio Azteca is a criminal organization that has significantly evolved since its inception as a prison solidarity group—first into a true prison gang and then into an organized criminal enterprise operating in the free world. Today, Barrio Azteca has declined in power and effectiveness in carceral settings but continues to play an important role in the wholesale and retail drug trade in the Paso del Norte area. Its organizational life cycle appears to parallel that of a licit enterprise, except that it primarily competes in the criminal protection marketplace. Thus, to survive and compete in the market for criminal protection, Barrio Azteca adapted to shifts in control dynamics, demonstrating uncommon resilience, first specializing in protection in response to changes in carceral violence and, later, expanding into the drug-trafficking market in response to violence in the criminal underworld both inside and outside prison. This article traces that history of adaptation and persistence, situating it within a synthesis of currently accepted theoretical models of criminal organizational evolution, and in so doing, provides the first organizational history of a prison gang—Barrio Azteca—published in the academic literature.