A research project, “Interconnected Inequalities and Family Life Courses in Spain” (INTERINEQ) headed by Andrés Castro, a researcher at the Centre for Demographic Studies (CED) offers a new look at the transition to adulthood and low fertility in Spain. From a quantitative and multivariate perspective, this study identifies six social classes among people aged between 29 and 35 in Spain: one consolidated upper class, three middle classes, and two lower classes. The research shows that plans for having a family and their coming to fruition depend on these social classes and, in particular, on the relative advantages and disadvantages in the middle classes. Relative disadvantages are associated with late emancipation and couple formation, and fewer children than desired. In the lower classes, there are no delayed family formation patterns or fertility gaps.