We draw upon the life-course perspective and examine whether Attention Deficit Hyperactivity Disorder (ADHD) moderates the age pattern of adult mortality using data from the 2007 and 2012 National Health Interview Survey Sample Adult File linked to National Death Index data through 2015. Overall, 7.0% of respondents died by 2015. Discrete-time hazard analysis indicates that the log odds of mortality were significantly lower among 18 and 19 year old adults ever diagnosed with ADHD and significantly higher among 46 to 64 year old adults ever diagnosed with ADHD, with a crossover occurring at age 33. Results were similar among men and women. It is not known specifically which risks drive changes in the risk of mortality documented among persons with ADHD during the transition to adulthood, the increased risk of mortality in midlife, or whether some risks operate more or less at particular ages. Additional research can lead to targeted, age- and life-course stage-focused interventions for specific risks and contribute to the reduction of ADHD-related mortality.