While many extoll the potential contribution of risk assessment to reducing the human and fiscal costs of mass incarceration without increasing crime, others adamantly oppose the incorporation of risk assessment in sanctioning. The principal concern is that any benefits in terms of reduced rates of incarceration achieved through the use of risk assessment will be offset by costs to social justice—which are claimed to be inherent in any risk assessment process that relies on variables for which offenders bear no responsibility, such as race, gender, and age. Previous research has addressed the variables of race and gender. Here, based on a sample of 7,350 federal offenders, we empirically test the predictive fairness of an instrument—the Post Conviction Risk Assessment (PCRA)—that includes the variable of age. We found that the strength of association between PCRA scores and future arrests was similar across younger (i.e., 25 years and younger), middle (i.e., 26–40 years), and older (i.e., 41 years and older) age groups (AUC values .70 or higher). Nevertheless, rates of arrest within each PCRA risk category were consistently lower for older than for younger offenders. Despite its inclusion of age as a risk factor, PCRA scores overestimated rates of recidivism for older offenders and underestimated rates of recidivism for younger offenders.