This paper seeks to analyse how electoral quotas for women have influenced processes of candidate selection within Belgian political parties as a consequence of the gender quota act adopted in 2002. The research covers eight parties in Belgium, and is articulated around three central questions in the research field of candidate selection. First, it analyses the composition of selectorates, in particular in terms of gender. Second, it aims to grasp the mechanisms at work in the within-party processes of candidate selection that facilitate or bar access for women to the lists, focusing on the implementation of gender quotas rules Third, it examines the outcome of the selection process, namely to what extent women are selected as candidates (on eligible places). For each question, the paper takes a comparative perspective along two lines of comparison. On the one hand it looks at potential differences that may exist between Flemish and francophone political parties – as the latter operate within the same set of institutional rules, and yet may differ in their implementation of electoral gender quotas. On the other hand it looks for differences depending on the parties’ ideological position, with a focus on the left-right ideological continuum. Using data from both face-to-face interviews among Belgian politicians (female and male) and party statutes, the paper qualitatively uncovers the actual mechanisms at work within the respective party organisations.