Research about school choice often leaves gender out of the equation. This omission becomes salient in a context in which a gender gap affects girls at school. Among the proposed interventions, single-sex schooling—its advocates say—emerges as a convenient proposal, as it is related to several advantages for girls, particularly disadvantaged ones. Some experts argue that enrolling their daughters in single-sex schools requires parents to make a pro-academic choice, which contributes to the creation of an environment that explains those advantages. This pro-academic choice assumes that parents know the advantages that single-sex schools offer to girls beforehand, and sustain several positive beliefs towards them. To explore this rationale, reasons for enrolling their kindergarten daughters in an all-girls school were collected among a group of parents (n = 18), and compared to parents’ (n = 17) of girls enrolled in a coeducational school. Both schools served a working-class population. Descriptive statistics and inferential analysis showed that for parents of single-sex schoolgirls, the most important reasons were pedagogical (curriculum, achievement, teachers) and pragmatic (near home, free). Only parents’ age was associated with preference for single-sex schooling. Nonetheless, the parents of the all-girls school hold positive beliefs regarding this type of education.