Standard Spanish has a binary grammatical gender system mandating agreement across pronouns, articles, nouns, and adjectives. For plural human­ referent nouns, a notable asymmetry exists: the feminine (las amigas) is exclusive to females, while the masculine (los amigos) is the unmarked, generic form for all-male, mixed-gender, or unspecified-gender groups (RAE, 2009). Nonetheless, non-standard neutral forms (e.g., les amigues) are gaining currency despite prescriptive exclusion. This novel use for the -e(s) suffix can be potentially interpreted either as a marked non-binary gender form, or as a neutral, non-marked form including any gender. Therefore, its cognitive processing and semantic function are ambiguous: is it a new competing generic form or a specific marker for individuals beyond the gender binary? This study explores this ambiguity in native Mexican Spanish speakers using self-paced reading and gender-assignment tasks to test plural nouns with masculine (-os), feminine (­as), and neutral (-es) endings.