I outline of an account of social entities. I show that they can have powers that are not the powers of their parts, nor their mere aggregation. This means that they cannot be reduced to their constituents. I use the example of public health to illustrate how the powers of social entities can work: how racismRaceracism, for instance, can have effects on individual human bodies. This justifies the study of social phenomena in addition to the study of individual people and middle-sized concrete entities, and in addition to the study of fundamental physics. Certain problems, including health, economy, and even language, are only explained in terms of social entities. We have good theoretical grounds, therefore, for rejecting methodological individualism.