Societal aging raises challenging ethical questions regarding the just distribution of health care between young and old. This article considers a proposal for age-based rationing of health care, which is based on the prudential life span account of justice between age groups. While important objections have been raised against the prudential life span account, it continues to dominate scholarly debates. This article introduces a new objection, one that develops out of the well-established disability critique of social contract theories. I show the implications of this critique for the prudential life span account and for the special case of age-group justice. The result is that age-based rationing based on the prudential life span approach is not supported, and that the prudential life span approach itself is not the best way to think about allocating health care between age groups. I propose an alternative approach that avoids the disability objection, and consider its implications for specific proposals for age-based rationing of health care.