Studies of US intergenerational mobility focus almost exclusively on the transmission of (dis)advantage from parents to children. Until very recently, the influence of earlier generations could not be assessed even in long-running longitudinal studies such as the Panel Study of Income Dynamics (PSID). We directly link family lines across data spanning 1910 to 2013 and find a substantial “grandparent effect” for cohorts born since 1920, as well as some evidence of a “great-grandparent effect.” Although these may be due to measurement error, we conclude that estimates from only two generations of data understate persistence by about 20 percent.