Recent advances are reviewed in understanding the heightened prevalence of psychopathology and maladaptive behavior among children with intellectual disability. Researchers have traditionally emphasized measurement and prevalence issues, using either psychiatric assessments or rating scales to identify the prevalence of various problems in children with intellectual disability. Yet the time is ripe to shift directions, and identify more precisely why children are at increased risk for psychopathology to begin with. Although several “bio- psycho-social” hypotheses are reviewed, a particularly promising line of work links psychopathology to genetic intellectual disability syndromes. Psychiatric vulnerabilities in several syndromes are reviewed, as are the advantages of phenotypic work for understanding psychopathology among children with intellectual disability more generally.