|Abstract:||The objective of this study was to assess the relationship between children's cognitive disability and parents’ age at birth. I conducted an analysis of data from the 2008-2010 American Community Survey for children aged 5 to 11 living with married parents, estimating cognitive disability rates by parents’ age at birth, controlling for other demographic characteristics. Cognitive disability rates according to parental age ranged from 0.8% to 6.8%, with an overall rate of 2.3%. Rates were much more strongly related to mothers’ age at birth than to fathers’ age at birth. The odds of cognitive disability were highest for children whose mothers were age 45 or higher at the time of their birth (odds ratios about 2.5 relative to age 30-34) and lowest for those born to mothers in their early 30s. Although mothers’ age had similar effects on boys and girls, fathers’ age was only associated with the odds of boys’ cognitive disability, once demographic controls were added. Some risks of having children at older ages are widely documented, but the pattern for all cognitive disabilities according to both mothers’ and fathers’ age is not well known. Recent attention has focused on children's disabilities that may result from de novo mutations occurring in men's sperm as they age, increasing the risk of such conditions as autism spectrum disorders and schizophrenia. However, these results demonstrate that overall risks are much more strongly associated with mothers’ age at birth, consistent with the effects of mothers’ health at birth on their children. Still, the effect of fathers’ age on boy’s cognitive disabilities is consistent with recent research on autism and schizophrenia, which are more common among boys.