A long-standing consensus among sociologists holds that educational attainment has an equalizing effect that increases mobility by moderating other avenues of intergenerational status transmission. This study argues that the evidence supporting this consensus may be distorted by two problems: measurement error in parents’ socioeconomic standing and the educational system’s tendency to progressively select people predisposed for mobility rather than to actually affect mobility. Analyses of family income mobility that address both of these problems in three longitudinal surveys converge on new findings. Intergenerational mobility is significantly lower among high school dropouts than among others, but there are no significant differences in mobility across higher education levels. This is consistent with compensatory advantage processes among the least educated in which individuals from advantaged backgrounds use family-based resources to compensate for their lack of human capital.