The relationship between the socio-economic status of parents and children is referred by the literature as intergenerational social mobility. The scope of this mobility encompasses different aspects such as educational attainment, income, wealth, prestige and occupational status. In particular, intergenerational occupational mobility is an interesting topic in the economic literature because it is positively associated with the economic achievement and the professional success. Low mobility implies that human capital, skills and talent can be misallocated. As a consequence, the workers’ efforts, their motivation and productivity could be negatively affected, which would have adverse effects on the economy growth and its competitiveness. This paper attempts to carry out the study of the evolution of intergenerational social mobility in Spain during the 21st century. The methodology applied involves to associate the National Classification of Occupations (CNO-94) with the New International Socio-economic Index of Occupational Status (ISEI-08), in order to establish a socio-economic hierarchy. Afterwards, once the occupational ranking is defined, we use statistic and econometric methods to assess the occupational transitions between fathers and children and to analyse the covariates’ effects on these transitions, including as explanatory variable the children’s educational attainment. Data used corresponds to the 2005 and 2011 Living Condition Survey (INE, 2005, 2011). The results of the study are displayed by distinguishing children according to their birth cohort.