This work combines cross-sectional and longitudinal income data to present the evolution of absolute intergenerational income mobility in several developed economies in the 20th century. We show that detailed panel data are unnecessary for estimating absolute mobility in the long run. We find that in all countries absolute mobility decreased during the second half of the 20th century. Increasing income inequality and decreasing growth rates have contributed to the decrease. Yet, growth is the dominant contributor to this decrease in most countries. We derive a model for the relationship between absolute mobility, growth, inequality and relative mobility. Ceteris paribus, absolute and relative mobility are inversely related.