Previous studies have recognized that occupational mobility varies with age, but studies have been impeded by imperfect measures of income to which career choosers respond. In this article, cohort changes for six age groups are viewed as resulting from responses to unobserved relative incomes in each of five decades. By an iterative procedure, leastsquares estimates can be obtained for ratios of age group response coefficients, and relative incomes are estimable down to a logarithmic transformation. Properties of the estimators are investigated. The analysis is applied to the U.S. and regions, and inferences are made about changes in the aggregate supply elasticity of farm operators and other conditions likely to prevail in the future.