We use linked parent-child administrative data for five countries in North America and Europe, as well as detailed survey data for two more, to investigate methodological challenges in the estimation of absolute income mobility. We show that the commonly used "copula and marginals" approximation methods perform well across countries in our sample, and the greatest challenges to their accuracy stem not from assumptions about relative mobility rates over time but from the use of nonrepresentative marginal income distributions. We also provide a multicountry analysis of sensitivity to specification decisions related to age of income measurement, income concept, family structure, and price index. (JEL D31, G51, I31, J12, J31, J62)