Background: The informant-based Anxiety, Depression And Mood Scale was translated into Dutch and its feasibility, reliability and validity in older adults (aged greater than or equal to 50 years) with intellectual disabilities (ID) was studied. Method: Test-retest (n = 93) and interrater reliability (n = 83), and convergent (n = 202 and n = 787), discriminant (n = 288) and criterion validity (n = 288) were studied. Convergent and criterion validity were studied for the Depressed mood and General anxiety subscales. Subgroups based on level of ID and autism have been made to study the criterion validity. Psychiatric diagnoses based on the PAS-ADD Interview were used as gold standard. Results: All subscales had good internal consistency (alpha greater than or equal to 0.80), excellent test-retest reliability (ICC greater than or equal to 0.75) and good interrater reliability (ICC greater than or equal to 0.74), except for the Social avoidance subscale (ICC = 0.57). The Depressed mood subscale showed low correlation (r = 0.44) with the self-report Inventory of Depressive Symptomatology, high correlation with the informant-report Signalizing Depression List for people with ID (r = 0.71) and no correlation with the PAS-ADD's sleep disorders subscale (r = 0.15). Its sensitivity ranged from 73 to 80%, and its specificity from 71 to 79%. The General anxiety subscale showed low correlation with the self-report scales: Glasgow Anxiety Scale (r = 0.37) and Hospital Anxiety and Depression Scale (r = 0.41), and no correlation with the sleep disorder subscale (r = 0.02). Its sensitivity ranged from 67 to 100%, and its specificity from 48 to 81%. Conclusions: The Dutch translation of the ADAMS is reliable and sufficiently valid to screen for anxiety and depression in older people with ID. (Contains 5 tables.)