Student learning in language-related subjects has become a gendered field, featuring higher participation rate and better performance by girls and women. Among others, the stereotypes depicting females as better language learners are thought to have led to such observed gender differences. Yet, few studies have examined the exact contents and effects of these stereotypes. This two-phase project investigated the issue using mixed-methods designs. In Phase 1, a questionnaire survey (Study 1) and semi-structured interviews (Study 2) were conducted simultaneously. MANOVA and thematic analysis were applied to two data strands, respectively. It was found that students, their guardians, and their teachers of English stereotypically considered females as better language learners in three dimensions: aptitude, achievement and affect. Additionally, a stronger stereotypical additive connection between affect and achievement was discovered, compared to that between aptitude and achievement. Phase 2 employed a sequential design. First, Study 3, a field experiment, uncovered gender-divergent effects of stereotypes on learners: results from a 2 (gender) × 2 (stereotype activation) between-groups ANCOVA indicated that male participants suffered from performance decrements in an English test after having been exposed to negative stereotypes. Female participants’ performance, instead, was marginally boosted. Subsequently, in Study 4, eight interviews with students in groups of three were carried out to explore students’ encounters with gender stereotypes concerning language learning. A range of cognitive, emotive, and behavioural responses were identified, indicating that the female stereotyping of language fields have been exerting predominantly adverse influences on boys and girls alike. This project has furthered scholarly understanding of gender stereotypes and language education. It also promotes a gender-equitable and -inclusive environment for language learners by highlighting the practical need for awareness-raising programmes sensitising students, guardians, and teachers to their gender-stereotypical beliefs and a synergy of intervention strategies targeting at each of the three dimensions of gender-language stereotypes (aptitude, achievement, and affect).