AbstractInflectional languages, and Romance languages in particular, display morphological variation in plural marking within the nominal domain. While standard varieties show plural inflection on all the constituents within theDP, other varieties show this plural marking only on some of its constituents. We investigate a set of puzzling data and propose that Number in Romance is not a head, but an adjunct, an optional and bi‐valent morphosyntactic feature. We single out the hypothesis that, within the nominal domain, thepluralizeris in unmarked cases adjoined to D (i.e., a categorizeddroot), and in marked cases it is adjoined to a noun or an adjective (i.e., a categorizedn/aroot). We also discuss that instantiations of plural marking within the nominal domain should be conceived as the output of morphophonological concord, a post‐syntactic operation that is sensitive to c‐command.