This article focuses on school-leavers who enter employment with a temporary contract in the European context, and examines their probabilities to shift to standard employment or unemployment, and their chances of occupational mobility afterwards. The authors argue that two institutional dimensions of insider–outsider segmentation drive the career progression after a flexible entry: the gap between the regulation of permanent and temporary contracts and the degree of unionization. The analyses show that a disproportionate protection of permanent compared to temporary contracts increases the probability of remaining on a fixed-term contract, whereas the degree of unionization slightly decreases the chance of moving to jobs with higher or lower socio-economic status. Finally, a shift to permanent employment after a fixed-term entry is more often associated with occupational upward mobility in strongly rather than weakly unionized labour markets.