This chapter analyses the ways in which environmental conservation activities were conducted in protected areas, considering the context of the pax narcotica since the 1990s. With the emergence of the National Commission for Protected Natural Areas, the institutionalisation of environmental conservation activities added another government entity to the drug trafficking scenario in Mexico. Methodologically, documentary analysis and interviews with senior inspectors in the protected areas are used to rescue experiences and document the forms of environmental conservation in contexts of insecurity and drug trafficking. This chapter documents how environmental conservation activities were affected by the presence of drug traffickers in protected areas and the working methods of each criminal group, as well as the ways in which inspectors and directors adapted to continue conservation activities within protected areas. In addition, this chapter discusses the prelude to the war on drugs in Mexico and its impact in the following decades on both public security and environmental conservation.