School books are pedagogical tools for the promotion of the principles set by the Brazilian National Curriculum Parameters (PCNs), and sexuality is a cross-cutting theme to be dealt with in school curricula. This study analyzed the quality of the discourse of a sample of school books used in Brazilian public schools, distributed by the Brazilian National Program of School Books (PNLD) and National Program of School Books for High School (PNLEM), as well as dictionaries distributed by PNLD and the National Program of School Libraries (PNBE). It was found that, while dictionaries convey clearly homophobic affirmations, school books are silent about sexual diversity and naturalize heterosexuality and gender binarism. Even though there are no homophobic assertions in the books, the affirmation of sexual diversity as a social value remains absent in the pedagogical material. There are two challenges in recognizing that homophobia should be fought against by formal education: the first is to break the silence about sexual diversity in the books; the second is to find rhetoric mechanisms to present it in the matrix of the promotion of equality and diversity.