The systematic study of immigrants’ economic assimilation requires an analysis of both intra- and intergenerational mobility, that is, of the progress made by each immigrant generation over the course of their own lives and relative to their parents. We examine both types of mobility using a unique dataset linking respondents of multiple waves of the Current Population Survey to their longitudinal tax records. This longitudinal information allows us follow individuals’ earnings trajectories and measure the extent to which second-generation men are able to reduce the earnings gap with later generations during their lifetimes. To overcome the limitations of previous studies examining intergenerational mobility, we match a sample of second- and later-generation children to their actual parents. Our matching strategy allows us to identify the exact third generation and to evaluate the contribution of ethnic attrition. We find large ethnoracial disparities in earnings mobility. Second-generation Hispanic men experience the same or greater intergenerational mobility than later-generation Whites after controlling for parental education. However, the earnings progress of second-generation Hispanics appears to stall or reverse during the course of the second generation even after controlling for education, suggesting that differential treatment in the labor market plays an important role.