The treaty that ended the Pacific War that began in 1879 established that Peru “perpetually and unconditionally ceded the territory of the coastal province of Tarapacá” and that the provinces of Tacna and Arica would belong to Chile for ten years from the date of the ratification of the Treaty. Once the deadline had expired, a plebiscite would be held in which the Ariqueños and Tacneños residents would determine their definitive membership by voting. The lack of a protocol delayed the completion of the plebiscite—which ultimately did not take place—for more than 40 years, but its imminence determined the policies implemented by both countries. Chile undertook the so-called “Chileanization”, a set of policies aimed at convincing potential voters of the advantages of choosing Chile as the country to which they wanted to belong. The Peruvian Government responded with actions that were carried out clandestinely in the occupied provinces. We will call them “Peruvianization” policies. I will deal with some of these policies and actions in this article.