The aim of the meta-analysis was to develop a mathematical model of the extent to which attention-deficit hyperactivity disorder (ADHD) prevalence decreases with age. In DSM-III, the category of residual attention-deficit disorder was defined to include adults who met full criteria for the disorder as children and have a partial syndrome as adults, but this category was removed from DSM-III-R. The strongest socio-demographic correlate of adult ADHD in the NCS-R was race-ethnicity, with non-Hispanic Blacks having significantly lower odds of the disorder than non-Hispanic Whites. Statistically significant comorbodities were found in the NCS-R between adult ADHD and a wide range of other DSM-IV/CIDI anxiety, mood, impulse-control, and substance use disorders. The NCS-R analysis also examined associations of adult ADHD with work performance. An analysis of work performance based on the WHO Health and Work Performance Questionnaire showed that ADHD was associated with an enormous amount of work role impairment.