Gender inequality remains an issue of high relevance, and controversy, in society. Previous research shows that language contributes to gender inequality in various ways: Gender-related information is transmitted through formal and semantic features of language, such as the grammatical category of gender, through gender-related connotations of role names (e.g., manager, secretary), and through customs of denoting social groups with derogatory vs. neutral names. Both as a formal system and as a means of communication, language passively reflects culture-specific social conditions. In active use it can also be used to express and, potentially, perpetuate those conditions. The questions addressed in the contributions to this Frontiers Special Topic include: • how languages shape the cognitive representations of gender • how features of languages correspond with gender equality in different societies • how language contributes to social behaviour towards the sexes • how gender equality can be promoted through strategies for gender-fair language use These questions are explored both developmentally (across the life span from childhood to old age) and in adults. The contributions present work conducted across a wide range of languages, including some studies that make cross-linguistic comparisons. Among the contributors are both cognitive and social psychologists and linguists, all with an excellent research standing. The studies employ a wide range of empirical methods: from surveys to electro-physiology. The papers in the Special Topic present a wide range of complimentary studies, which will make a substantial contribution to understanding in this important area.