The article presents the results of a research aimed at analyzing how economic and employment crisis in Spain has affected the labour trajectories of the population under 40 years. The trajectories during this period are analyzed from two points of view. First, descriptively, building a typology of trajectories and analyzing it in comparison with the population of more than 40 years. Second, causally, dentifying the factors that explain the different types of trajectories found. These analyses assess to what extent has been, during the period of crisis, a polarization between the trajectories of persons belonging to the younger cohorts and those belonging to the older ones. On the other hand, the analyses also assess whether it
has been a progressive gap within the younger cohorts on the type of trajectories developed. The results show that the «inter-generational polarisation» is given in a lesser extent than is often defended in the international literature, while the «intra-generational polarisation» is not really a polarisation, but a segmentation into three types. As to causal analysis, it is found that the classical variables of segmentation in the Spanish labour market have continued to influence the labour trajectories during the crisis. Factors such as sector or social origin have had also a causal effect.