This disseration is the result of an investigation of grammatical and psycholinguistic aspects of a phenomenon known as ellipsis. In particular, we address some potential undergeneration problems involving ellipsis in Brazilian Portuguese, that is, acceptable cases of ellipsis that, strictly speaking, should not be generated by grammar, since, at least apparently, they violate a condition of syntactic identity expected between the elided material and its antecedent. Regarding the discussion of grammatical aspects, we argue that some cases of mismatch between a elided vP and its antecedent should be appropriately analyzed as grammatical -the mismatch being merely apparent, and the syntactic identity of the elided material and its antecedent calculated virtually in terms of abstract grammatical representations. As for the psycholinguistic aspects of the phenomenon, our goal was to test some predictions made by a literature already concerned with undergeneration cases involving ellipsis (Cf. ARREGUI et al., 2006;KIM et al., 2011;PARKER, 2018). The main prediction tested was that there would be an evident misalignment between the grammar and the processing of ellipsis in Brazilian Portuguese. From three experimental tests (acceptability judgment data and reading time data were collected using a self-paced reading technique), we contrasted responses of the offline processing of ellipsis with responses of its online processing, and we verified a strong alignment between grammar and processing of the phenomenon in Brazilian Portuguese. Our findings are discussed in the light of the Lewis and Phillips's (2015) understanding, that grammatical theory and processing models are different aspects of the same cognitive system, but not different cognitive systems.