While the knowledge on how candidate selection happens begins to be rather organised, remarkably little attention has been paid to the selection criteria for candidates, “which one might have supposed was central” (King in Stark 1996, 124). Why do selectorates prefer some candidates and put others aside? What drives them? The dearth of knowledge of why some aspirants are chosen over others is puzzling when we consider the growing gap between citizens and elites together with the importance for the elected assemblies to be representative. This paper aims to investigate the informal selection criteria and questions on what basis political parties make their selection choices. Considering that selectorates may rely on individual characteristics of the candidates, but in a list system, that they might also want to ‘balance the ticket’, this research tackles criteria both at the individual and the aggregate levels. Based on the party strategic goals’ framework (Sjoblom 1968), the competition between aspirants at the selection stage is expected to revolve around the criteria of acceptability, electability and competence, in that order of importance. I study the case of the Belgian francophone green party Ecolo, where the selection process involves both an exclusive and an inclusive selectorate. In-depth interviews with party selectors constitute the empirical basis of the analysis and deepen our knowledge as to whether some profiles of citizens are more likely to be selected, and thus face better chances to enter the parliament.