Probably the most universally supported conception of justice in advanced societies is that of equal opportunity. What does this mean, and how can it be formalized? The first treatment of this problem in social choice theory involved interpreting equality of opportunity as equality of opportunity sets, that is, rendering the sets of choices available to di¤erent individuals the same. In my view, this literature was too abstract – it failed to take su‰cient cues from popular and long-standing conceptions of equality of opportunity. A consequence of this over-abstractness is that no empirical work, on what equal-opportunity policies should be in real-world situations, has followed from this work, as far as I am aware. Those popular conceptions have, in contrast, influenced greatly the recent literature in egalitarian political philosophy, particularly the idea that in the equal-opportunity ethic, there is, as well as a desire to equalize something, an insistence that individuals be held responsible for what happens to them. This is popularly formulated in the ‘level-the-playing-field’ metaphor: equalopportunity policy must create a level playing field, after which each individual is on his own – what outcomes finally occur will reflect individual e¤ort, and outcome di¤erentials are ethically acceptable, if the playing field was initially level, and if they are due to di¤erential e¤ort. John Rawls (1971), in his path-breaking work, certainly understood, and supported, the idea that the social mandate to equalize outcomes across indi-