Résumé : Gender quotas are used worldwide as an instrument to increase the number of women in the elected offices. Gender quotas exist under multiple forms, they thus do not have the same impact on the representation of women. Focussing on the number of parliaments, the main question of this paper is whether the legislative quotas adopted in the Law or Constitution and the voluntary quotas adopted by parties have an impact on the number of women who are elected to the parliament. Focussing on countries of Europe, this paper analyses the positive empirical impact of gender quotas on women’s parliamentary representation, together with the history of the different quota implementation. Since the Nordic countries have great female representation and they only adopted voluntary party quotas, similar countries might present the same results. Scandinavian countries are an exception, since Western European countries do not have the same positive percentage of women in their parliaments. Since legislative quotas are inscribed in the law or the Constitution, their application is mandatory, and women may thus be better represented. It seems this variable had a positive impact on women’s parliamentary representation, however the process is slow. Therefore, a combination using both the legislative quota and the voluntary quota should lead to a great empirical improvement. Taken separately the quotas have little impact, however together they result in high growth regarding the percentage of women in parliaments. Although quotas are supposed to be temporary, nothing indicates that they will be removed anytime soon. On the contrary, new measures and improvements are appearing.