This article presents a comparative study on how textbooks of Portuguese and Spanish language handle mode and tense variation.. We took as theoretical background both studies on variation and teaching by Labov (1972, 1978 and 2003), and what official documents states about the teaching of foreign languages in Brazil. The research followed explicit instructions we developed for the analysis of norm/use, change, linguistic and extra-linguistic constraints, the use of authentic texts and variation between verbal tenses. The results obtained underlined that the themes in question were handled only partially by the textbooks: the text is still used as a pretext; when there is a theoretical explanation on variation, it appears only in the chapter at issue, not been applied throughout the book; the effects of meanings of the diverse verbal forms in the communicative context are also not substantiated. However, in the textbook Hacia el español, we were able to verify an effort in the sense of making students aware of the linguistic variation in phonetic and phonologic, lexical and morphosyntactic levels.