Intergenerational mobility has been a topic of persistent interest in sociology and, increasingly, in economics. Nearly all of these studies focus on fathers and sons. The possibility that intergenerational mobility is more than a simple twogenerational AR(1) process has been difficult to assess because of the lack of the necessary multi-generational data. We remedy this shortcoming with new data that links grandfathers, fathers, and sons in Britain and the U.S. between 1850 and 1910. This permits an analysis of mobility across three generations in each country and a characterization of the differences in those patterns across two countries for which we have found substantial differences in two-generation mobility in previous work. We find that, in both countries, grandfathers mattered: even controlling for father’s occupation, grandfather’s occupation significantly influenced the occupation of the grandson. For both Britain and the U.S. in the second half of the nineteenth century, therefore, assessments of mobility based on two-generation estimates significantly overstate the true amount of mobility.