On average, adults with intellectual disability (ID) have higher mortality risk than their peers in the general population. However, the effect of age on this mortality disadvantage has received minimal attention. Using data from the 1986-2011 National Health Interview Survey-Linked Mortality Files (NHIS-LMF), discrete time hazard models were used to compare mortality risk for adults with and without ID by age and gender. Increased mortality risk was present for all adults with ID, but was most pronounced among younger age females. The mortality differential between those with and without ID diminished with increased age for both females and males. Findings support the argument that heterogeneity of frailty may explain differences in mortality risk between those with and without ID.