Family formation, a process that includes union formation, fertility, and their timing and order, has become increasingly diverse and complex in Europe. We examine how the relationship between socio-economic background and family formation has changed over time in France, Italy, Romania, and Sweden, using first wave Generations and Gender Survey data. Competing Trajectories Analysis, a procedure which combines event-history analysis with sequence analysis, allows us to examine family formation as a process, capturing differences in both the timing of the start of family formation and the pathways that young adults follow. Regarding timing, socio-economic background differences in France and Sweden have remained relatively small, whereas in Italy and Romania higher parental education has become more strongly associated with postponement. Pathways tend to diverge by socio-economic background, particularly in Sweden and France. These results indicate that while family formation patterns have changed, they continue to be stratified by socio-economic background. [ABSTRACT FROM AUTHOR]