Departing from the welfarist tradition, recent theories of justice focus on individual opportunities as the appropriate standard for distributive judgments. Justice is seen as requiring equality of opportunity, instead of outcomes, among the individuals. To explore how this philosophical conception can be translated into concrete public policy, we select the in-come as relevant outcome and the income tax as the relevant redistributive policy, and we address the following questions: (i) what is the degree of opportunity inequality in an income distribution? (ii) how to design an opportunity egalitarian income tax policy? Both positive and normative criteria for ranking income distributions on the basis of equality of oppor-tunities are derived. Moreover, we characterize an opportunity egalitarian income tax policy and we formulate criteria for choosing among alternative tax systems.