This article relies on a prospective qualitative study, that provides valuable insight into the mechanism through which the meaning of holidays is built over time. Following a life course perspective, the article analyses the continuities as well as the twists and turns of the meaning of Christmas in relation to significant turning points that occur along the paths of individual lives in transition to adulthood. Grounded on an inductive approach, the study draws on longitudinal qualitative data collected through solicited diaries, kept by 14 young Romanian adults, around Christmas time, along four panel waves (2004, 2010, 2016, 2020). Results show that there is no universal configuration of the meaning of Christmas, but rather a diversity of personalised dynamic configurations, in line with individuals’ subjective realities, which are sensitive to family traditions passed down during socialisation, and constantly updated with each generation that assumes them, but also to significant life events that occurred on their early adult life course trajectories, determining a re-evaluation of attitudes about self, life, religion and others. The article concludes that Christmas, as a social construct, is a malleable bearer of values, which acts both as a ‘sword’ and as a ‘shield’ that diarists use according to the needs, wishes and challenges that arise in their transition from adolescence to enhanced adulthood.