In the late 20th century, there have been major social transformations in European societies but the new status of women is one of the most outspoken ones. In most advanced Western democracies, new cohorts of female political participants have been socialised in societies with drastically increasing levels of education for women, increasing degrees of female labour market participation, more egalitarian gender roles, and where politics is not just a men’s business anymore. However, existing analyses of participatory gender inequalities rarely take on a larger historical perspective to take into account social change, such as the changing role of women in society and generational change, since most of them are single-country studies with a cross-sectional research design. Hence, none of these studies do make comparisons over time and as a consequence they do not distinguish between the impact of cohort, life cycle and period effects for participatory gender inequalities. This paper proposes therefore a longitudinal and comparative research design to investigate how generational replacement shapes the evolution of gender differences in political participation in Western Europe. Theoretically, it aims to test the hypothesis on the existence of a “gender generation gap” in political participation in Western Europe. Empirically, it distinguishes cohort from life cycle and period effects. Yet, any model that includes all three effects will be “underidentified” since one is unable to tell from survey data which of the three factors of age (years since birth), period (survey year), or cohort (birth year) is generating any changes to the dependent variable, here political participation. In fact, the well-documented problem with age-period-cohort (APC) models is that only two of the basic effects can be identified. This paper resolves this methodological problem by using Elias Dinas’ and Laura Stoker’s design-based approach to identifying cohort effects in APC analyses (Dinas and Stoker 2014) and by using existing longitudinal and comparative survey data from the European Values Study (1981-2008).