Expanding and Measuring Opportunitiesis a working paper for the Center for Development and Enterprise. The idea that circumstances and free choice can be neatly divided is open to considerable debate. The [equality of] opportunity framework begs the question, ‘what is in the control of the individual?’ Regardless, equality of opportunity is about ‘birth luck egalitarianism’-minimizing the variance of birth luck-- while maximizing or expanding opportunity is about efficiently raising the average birth luck. One advantage of ‘opportunity expansion’ over ‘opportunity equalization’ is that an accounting between free will and determinism is unnecessary–there is no concern with estimating the impact of genetic or in utero factors on outcomes, for example. However, if we are worried about maximizing or expanding opportunities rather than equality of opportunities, the approach that is appropriate when defining equal opportunity (the state when measured exogenous factors have no bearings on relative outcomes within a country) does not work. This is because we cannot take the stock (or flow) of outcomes as a given or an irrelevance. Empirically, allowing the stock of outcomes to vary suggests a goal of expanding or maximizing opportunity may involve a markedly different set of policies than equalizing opportunities. This is because variance in opportunities within countries is far smaller than variance across countries. That implies a focus on raising national average opportunity may have a far bigger payoff than redistributing opportunities or trying to raise the minimum opportunity to the mean within a country --although greater equality of opportunity is likely to be a method to increase absolute levels of opportunity.