There are two prominent approaches to defining equality of opportunity: The ex-ante approach is based on the idea that the set of opportunities open to individuals in a given type, before they exert any effort or make any choices, should be of equal value. Ex-ante inequality of opportunity is then the inequality between the values of these opportunity sets, often represented by the average income for each type. The ex-post approach is based on the idea that the outcomes of individuals exerting the same degree of effort (or responsibility) should be equal. If one takes the relative position (or rank) of a person in her type’s income distribution to be an indicator of her relative effort, then ex-post inequality of opportunity is just an aggregation of differences across these distributions, at each and every rank.