Although interest regarding gender role portrayals in advertising has persisted for many years, the degree of gender stereotyping in advertising, possible changes of gender stereotyping over the years, and the nature of the relationship between gender stereotyping in advertising and role changing developments in society have not yet been studied in previous research. To address these issues, this study provides a meta-analysis of the research on gender roles in TV and radio advertising based on 64 primary studies. The results show that stereotyping is prevalent in advertising. Stereotyping occurs mainly related to gender’s occupational status, meaning gender equality in advertising is least likely in an area that is the primary concern of gender-related politics. Stereotyping in advertising has indeed decreased over the years, although this decrease is almost exclusively due to developments in high masculinity countries. The results of a correlation analysis and a simultaneous equation model show that gender stereotyping in advertising depends on gender-related developments and value changes in society rather than the other way around. These results provide for the first time empirical support for the mirror argument over the mold argument in the long-standing debate about advertising’s consequences for society. The findings further provide implications for researchers, public policy makers, and marketing practitioners.