This article investigates whether experiences of the PhD trajectory during the first year of enrolment predict dropout during a later stage. More specifically, we studied how supervisor support, time pressure and passion for research relate to dropout among PhD students and assessed the role of discipline in this process. We used longitudinal data from four waves of the PhD Survey (2018 through 2021; N = 589), conducted at a university in Belgium, as well as administrative data on the enrolment status. Results show that supervisor support is negatively related to dropout, and that this is especially important for PhD students in the human sciences. Time pressure is positively related to dropout. When stratified by scientific discipline, this effect was only significant for PhD students in human sciences and in the life sciences and medicine. Passion for research showed a negative association with dropout. Stratification by discipline showed that this effect was only found among PhD students in natural sciences and engineering. Furthermore, teaching assistants showed higher dropout rates, and female PhD students in human sciences and life sciences and medicine were less likely to drop out.