In a world of limited resources, competition between the young and old prompt difficult questions of justice. In countries with public pension and health care systems, or with aging populations, there is often a concern that members of different generations are not always treated fairly. Dennis McKerlies monograph examines justice between age-groups with the ultimate goal of a new theory of justice that effectively grapples with those questions. In the realm of public policy and medical ethics this is an important and timely topic, but surprisingly one that has received relatively little attention from moral philosophers. McKerlie develops a comprehensive view of fairness between age groups that applies the egalitarian values of equality, or priority for the badly off, to temporal parts of lives -- not just to complete lives.