In this text, are presented search results which aims to contribute to the understanding the teaching of Portuguese in the schooling of children in the São Paulo state, Brazil, and to problematize how this teaching was associated with projects of formation of the Brazilian citizen and construction of an ideal of nation. For this, it is focalized aspects about the teaching of Portuguese contained in the report prepared by Rui Barbosa in 1882 and the prescriptions for this teaching contained in two programs implemented in São Paulo after the establishment of the Brazilian Republic in 1889. By means of historical approach, it was collected different types of documents related to the teaching of Portuguese in primary school in São Paulo, among which this report and these teaching programs. The analysis of these documents, based on Cultural History and History of Curriculum and School Subjects, has made it possible to note the following aspects: at the end of the 19th century, in the Brazilian imperial period, Rui Barbosa elaborated in 1882 the report Reforma do ensino primário e varias instituições complementares da instrucção publica. This report presents innovative and visionary conception for Education in Brazil. In it, the language is understood as "vehicle of thought" and "educator of the human race". For this reason, Rui Barbosa criticizes grammar teaching and argues that the teaching of Portuguese should focus on the intuitive processes and the practice of enunciation. Although formulated at the end of the Empire, this report became emblematic in the States debates about the directions of education and nation building after the Establishment of the Republic in Brazil. In São Paulo, After the republican reform of Public Instruction, it was promulgated in 1894 the Programma das escolas preliminares that presents details of the contents of each primary course subject. In this program, following the Rui Barbosa report, the teaching of Portuguese should include exercises centered on the enunciation of letters and words, for later work with reading and writing sentences or compositions. In 1905, this program was revised with the publication of the Programma de ensino para grupos escholares e eschola-modelo. In it, the teaching of Portuguese consists in practices related to reading and uttering words and sentences and in the most advanced series practices involving declamation and composition of prose and verse texts. The results obtained through the analysis of these documents make it possible to understand the meaning of the teaching of Portuguese in the primary school in São Paulo after the implantation of the Republic and also the advent of Linguistic Science (in tune with republican positivism). These teaching programs, "inspired" in the Rui Barbosa report, represent a form of state control and indicate the belief in legislation as an instrument of socio-cultural change of the country. In this way, the teaching of the Portuguese was highlighted; it was the "central force of remarkable power in education" (and the strength of the Republic).