Amidst social changes in gendered language use, there is pushback from institutions such as the Spanish Royal Academy, which claims that the use of the generic masculine (e.g., bomberos ‘firemen’) in describing a mixed-gender group is equally inclusive of both men and women (Bosque 2012). By contrast, speakers of Spanish have increasingly adopted gender-inclusive alternatives to the generic masculine (e.g., bomberos o bomberas; Bengoechea 2015). Across two behavioral tasks, we investigated whether gender-inclusive forms actually lead to more inclusive interpretations. We found that the use of the inclusive form (by contrast to the generic masculine) indeed yields more inclusive interpretations, increasing the inferred femaleness of stereotypically male professions, but also decreasing the inferred femaleness of stereotypically female professions. In an attempt to explain the reasoning that delivers inclusive interpretations, we developed a computational cognitive model of the reasoning process. Our model treats the phenomenon as an instance of a markedness implicature: speakers use the longer, inclusive form to guide listeners away from their prior expectations. This work highlights the need for further research into the use of gender-inclusive language cross-linguistically, as well as for pushback against prescriptive institutions perpetuating stereotypes.