It is often pointed out that conclusions about intergenerational (parent – child) mobility can differ depending on whether we base them on studies of class or income. We analyze empirically the degree of overlap in income and social mobility and we demonstrate mathematically the nature of their relationship.. Analyzing Swedish longitudinal register data on the incomes and occupations of over 300,000 parent-child pairs, we find that social mobility accounts for up to 49 per cent of the obs...