The Harlingen Convention, a statewide political meeting called to discuss organizing against racial discrimination, was held at the Harlingen Auditorium on August 14, 1927. It was called by El Comité Provisional Organizador Pro-Raza, headed by Alonso S. Perales. Felipe Herrera of Harlingen acted as secretary. El Comité's membership consisted of Mexican Americans and Mexicans from Mercedes, Weslaco, Brownsville, Edinburg, Mission, San Benito, Donna, and Raymondville. At least one member, M. Flores Villar, of Harlingen, was a Mexican citizen.
El Comité announced through the Spanish-language press that the "Pro-Raza" conference would resolve several issues. The English-language press also announced the meeting, and the McAllen Daily Press reported that a society of Mexican Americans was being formed. Conference planners extended an open invitation to all persons of Mexican descent, members of sociedades mutualistas, and civic or political organizations. Houston and Fort Worth societies elected delegates to attend. Key organizations in attendance included the Orden Hijos de América and the Order of Knights of America. Two hundred delegates attended.
Conference speakers included Eduardo Idar, Clemente Idar, José T. Canales, and Perales. After conflict over whether to let the Mexican citizens stay, as many as 90 percent of the participants walked out. When the membership vote occurred, those present determined that political organization necessitated the exclusion of Mexican citizens. Several newspapers criticized the conference and the decision to include only United States citizens. M. Flores Villar, a writer for El Comercio of Harlingen, and Carlos Basáñez Rocha, of México en el Valle, published in Mission, argued that Canales made derogatory remarks about Mexicans. They also charged that there were voting irregularities. Perales wrote his version of conference events for El Cronista del Valle, a Brownsville newspaper. He worked with the McAllen chapter of the League of Latin American Citizens and the Corpus Christi Orden Hijos de América to influence the Immigration Service in Brownsville to deport Villar and Rocha.
Shortly before the conference, the Corpus Christi Orden Hijos de América had invited Perales, J. Luz Saenz, and Herrera to dissuade Perales from the formation of another organization. Perales seems to have convinced the convention that there were problems with the Orden Hijos de América and the Order of Knights of America and that a new organization was called for. Delegates at Harlingen debated until midnight over a name, but could not agree. Perales provisionally called it the League of Latin American Citizens in subsequent correspondence. Chapters were later organized in McAllen, Laredo, Grulla, Encino, Harlingen, Penitas, and Gulf; the umbrella organization merged with other groups in 1929 to found the League of United Latin American Citizens.