Brazilian Portuguese possesses two forms used as 1st person plural pronouns: nós and a gente, both meaning ‘we’. The form nós has always been pronominal, whereas a gente is derived diachronically from the noun phrase a gente ‘the people’. In accord with this historical evolution, the standard language prefers the use of the 1st plural verb desinence -mos with nós, as in nós falamos ‘we speak’ or ‘we spoke’. The 3rd person desinence 0 is reserved for a gente, giving a gente fala ‘we speak’ as the preferred form. In popular speech both nós fala and a gente falamos are used frequently. We examine the use of these variable forms across four generations in Rio de Janeiro. In the older generations, phonic salience is the principal controlling factor for both nós and a gente. Since preterit desinences are stressed more frequently than present desinences, this induces a biased surface distribution, with -mos occurring more frequently with past tense reference. Nonetheless, for older speakers tense does not play a statistically significant role. In younger speakers, tense becomes statistically significant as a determining factor in the use of the desinences, with preterit favoring -mos for both subject forms. So far, there has been no change in the grammar itself, but the locus of determination of the use of -mos seems to have shifted from saliency to tense across the generations. One can speculate that some time in the future -mos may become a preterit marker.