Abstract: This dissertation analyzes the public interest discourse that accompanies the implementation of telecommunication institutional reforms in developing countries. Whereas previous research has focused on interpretations of the public interest concept by policymakers, this dissertation addresses the point of view of consumers affected by such reforms. Telecom reforms are often accompanied by official discourse emphasizing benefits in price, quality of service, and access that consumers expect to receive; this dissertation analyzes the extent to which consumers consider that these expectations have been fulfilled. The importance of the consumers' interpretation of the public interest is also emphasized by the increased attention of regulatory agencies and public utility commissions worldwide to consumer protection and education in the new regulatory environment. The dissertation focuses on the case of Mexico, a country representative of the political, economic, and social challenges faced by nations with low and middle levels of telephone penetration. Using argumentation analysis, the study reconstructs the consumers' public interest argument about telecommunications reform in Mexico, based on a purposive sample of letters to the editor published in the nationally distributed Mexican newspaper El Financiero from 1991 to 2001. The letters were coded to identify three parts of the consumers' argument: industry performance, recurrent themes, and values. Ninety-two percent of the letters were complaints about the service provided by Telf̌onos de México (Telmex), the incumbent local exchange operator; quality of service, both equipment-oriented and people-oriented, was the area of performance that consumers complained the most about. Thematically, consumers emphasized different aspects of their relationship with Telmex that made them feel powerless before the operator. In their view, Telmex's power over consumers was increased by its close relationship with the communications ministry. Consumers gave priority to values of interaction, such as respect, politeness, and responsiveness, which Telmex seemed to lack. Three main arguments emerged: (a) Telmex exercised power over consumers; (b) the government failed to fulfill the public's interest by facilitating abuses, and (c) consumers were victims of Telmex. I propose that for consumers in Mexico the public interest in telecommunications means empowering consumers before providers. Policy recommendations are given based on this finding.