We now know a lot about engagement in and around 1968 from the structural (the macrosociological conditions created by social turmoil at the time) and organizational (the groups in existence) points of view, and more recently about professional and political consequences for the militants. However, their affective career as a whole is basically unknown during a period considered to be when the private sector became politicized and, more especially, in a scientific context that has been characterized in the last couple of decades by an emotional or affective turn. Part of the reason for this gap is methodological because it is hard to pin down. Based on a corpus of almost 400 life stories, 78 % of which are accompanied by a timeline of the subject’s life, this article reflects on the pertinence and the difficulties of using a biographical tool and then suggests several empirical methods to enrich the tool and fill in any gaps.