This paper examines the broader concept of institutionalisation of gender equality in political office, which comprises, among other things, both gender quota reforms and levels of women’s representation. It focuses on Southern Europe, more precisely on the cases of Greece, Portugal and Spain. These countries offer the ideal research design as they have similar starting points but different results. When democracy was restored in the 1970s they shared similar political, cultural and socioeconomic traits, among them a consensual-corporatist type of democracy, the experience of a regime which reinforced the structural inequalities between the sexes while traditional patriarchal values were inoculated through the educational system and mass media, and very low levels of women in the first democratic parliaments. However, relevant differences exist regarding the institutionalisation of gender equality in political office. While Portugal and Spain recently adopted legislative quota laws, Greece did not. Furthermore, levels of women’s presence in national lower chambers enormously differ: for 2010, Spain counted with 36.3% of women deputies, Portugal 27.4% and Greece 17.3%. Following Krook (2009), this paper looks at a broad array of factors to explain dissimilar results which go beyond institutional variables (i.e. electoral system and institutional design) such as distinct dominant discourses on equality and group representation, the mobilization of the women’s movement and its alliances with party feminists, and the role of political parties.