The chapter presents a theoretical approach for Brazilian Portuguese (BrP) and English, Type I languages, i.e., languages where numerals and plural inflection engender two classes of noun (count and mass). However, only in BrP, plural inflection in the noun is optional, and Bare Singulars (BSs) are grammatical. The proposal is that noun phrases in English and in BrP are born as predicates. In English, the first layer of the noun projects atomicity; in BrP, the determiner projects atomicity. Thus, in English, BSs are always atomic predicates and cannot be in argument position. In BrP, atomicity is not projected by the noun, so the noun, which is a cumulative predicate, is shifted to a kind individual when it occurs in argument position. This account explains the different interpretation of the BS in English and in BrP. The model is extended to explain plural inflection and DPs headed by definite articles in both languages. The chapter develops two approaches to BrP determiner phrases: a constructional approach and a presuppositional one. It explores the idea that there is microparametric variation accounting for two types of languages: noun-centered languages, English, and determiner-centered languages, BrP.KeywordsBare nominalsDeterminer phrasesSemantic variationPolysemyAtomicity