This qualitative case study focuses on the development of women’s political representation in national legislation, from 2000 to 2021 in Mexico. To examine the development of women’s political representation, this study will use Hanna Pitkin’s (1967) four interconnected diminutions of representation: formal, descriptive, substantive, and symbolic representation. The result of this study has revealed a predominantly positive development trends in Mexican women’s political representation in the Congress of the Union, from 2000 to 2021 in terms of formal, descriptive, substantive representation. While the implantation of a gender quota system has had an overall positive impact, the unwavering scepticism and lack of trust of the democratic and representative political institutions, among women is still persistent.