This paper contributes data from Paraguayan Guaraní (Tupí-Guaraní) to the discussion of how temporal reference is determined in tenseless languages. The empirical focus of this study is on finite clauses headed by verbs inflected only for person/number information, which are compatible only with non-future temporal reference in most matrix clause contexts. The paper first explores the possibility of accounting for the temporal reference of such clauses with a phonologically empty non-future tense morpheme, along the lines of Matthewson’s (Linguist Philos 29:673–713, (...) 2006 ) analysis of a similar phenomenon in St’át’imcets (Salish). This analysis is then contrasted with one according to which temporal reference is not constrained by tense in Paraguayan Guaraní, but only by context and temporal adverbials. A comparison of the two analyses, both of which are couched in a dynamic semantic framework, suggests empirical and theoretical advantages of the tenseless analysis over the tensed one. The paper concludes with a discussion of cross-linguistic variation of temporal reference in tensed and tenseless languages. (shrink)