It is commonly thought that exploitation is unjust; some think it is part of the very meaning of the word ‘exploitation’ that it is unjust. Those who think this will suppose that the just society has to be one in which people do not exploit one another, at least on a large scale. I will argue that exploitation is not unjust by definition, and that a society might be fundamentally just while nevertheless being pervasively exploitative. I do think that exploitation is nearly always a bad thing, and wul try to identify the moral belief which makes most of us think it is. But I will argue that its badness does not always consist in its being unjust.