Evidence has accumulated that the parents of children with intellectual disabilities are at increased risk of adverse mental health outcomes including depression and anxiety. Research in the field is currently attempting to explore the nature of this association, trying to identify which parents are most at risk and to what extent is the association confounded by the family environment, genetics and prior episodes of adverse mental health. The ALSPAC cohort has not been used to explore this research question so far and has substantial information on the family environment, parental mental health before and after the development of an intellectual disability in the child, maternal genetics and child behaviours. Such information may be useful for identifying modifiable targets for intervention or exploring which parents are most at risk.