Using harmonized household survey data, we analyze long‐run social mobility in the United States, the United Kingdom, and Germany, and test recent theories of multigenerational persistence of socioeconomic status. In this country comparison setting, we find evidence against a universal law of social mobility. Our results show that the long‐run persistence of socioeconomic status and the validity of a first‐order Markov chain in the intergenerational transmission of human capital is country‐specific. Furthermore, we find that the direct and independent effect of grandparents' social status on grandchildren's status tends to vary by gender and institutional context.