In this work, carried out on a corpus of opinion texts produced by students of Portuguese as a Foreign Language, at level B1, whose theme focused on a comparative perspective between two cultures, native and host, we proceeded to a descriptive-qualitative analysis of of modifying mechanisms of illocutionary force, attenuation and reinforcement, which the students resorted to. The results allowed to observe that the students resort mainly to assertive and expressive acts in the production of opinion texts, regulating their illocutionary force using essentially lexical mechanisms, to the detriment of semantic or morphological mechanisms. In addition, the epistemic modality assumes a predominance in relation to other types, although, in most evidence, there is no validation of the predicative relationship. To support this analysis, we used guiding readings on illocutionary acts (Searle, 1969), on their modalization (Corbari, 2013; Soares, 1998) and, specifically, on attenuation and reinforcement phenomena (Briz & Albelda, 2013; Albelda , 2005) and how they relate to the issue of modality (Campos & Xavier, 1991; Oliveira e Mendes, 2013) and how all these issues are referenced, in terms of pedagogical and didactic approach in the Common European Framework of Reference for Languages ( 2001).