This thesis extends an approach to justice grounded in the idea of agreement between equals to the question of justice between generations. Taking as its starting point the claim that distributive principles should be justifiable to all who will be subject to them - in this case, those who comprise the present and future generations - it begins by identifying two issues which militate against the extension of this method to the intergenerational context: the nonidentity problem and the mutuality problem. In order to overcome the non-identity problem I appeal to - and defend - the claim that it is possible to wrong future people without necessarily harming them: from this, it can be inferred that we have humanitarian obligations toward future generations, by virtue of their status as rights-bearers. I then begin my discussion of the mutuality problem with a critical assessment of the idea of a universal contract with transgenerational scope. Despite rejecting this approach, I suggest that it captures certain fundamental intuitions that we have toward future generations, which complement an analysis grounded in indirect reciprocity. In this way, the mutuality problem comes to occupy a position of centrality within the thesis. To resolve it, I expound a theory of intergenerational mutuality which, I argue, allows the intergenerational context to be analysed as a collective action problem - in accordance with the standard interpretation of the original position.