The conflict in the Basque country lasted for decades during the 20th century, whether in the northern Basque country or in the southern Basque country. Generations of activists have taken the path of illegal engagement in the defence of the Basque country. Recent studies have suggested that within ETA, generations of activists can be distinguished due to a certain relationship to violence (Della Porta, 2013). We undertook an empirical sociology survey of 64 members of illegal organizations in this territory. It showed that generational distinctions were rather based on variables such as the involvement of parents’ militant, the articulation between legal and illegal political involvement each militant had, the political project to which activists aspired, their relationship to ideology, their conception of the use of illegal political means, and the socio-political and structural context in which their action is embedded.