Background: When assessing the mental health needs of people who have intellectual disabilities (ID) it is important to use measures that have good validity and reliability to ensure accurate case recognition and reliable and valid outcome data. Measures developed for this purpose tend to be self-report or by informant report. Multi-trait screening tools developed to identify psychological and psychiatric disorders in people who have ID tend to be informant based. Research examining the concordance of different tools has found this to be high but not for specific diagnoses. Multi-trait self-report measures are fewer and have not been compared with informant approaches. This study aims to examine the concordance between two multi-trait measures of mental health used with people who have ID. One administered to informants [the Mini-Psychiatric Assessment Schedule for Adults who have Developmental Disabilities (PASADD)] and one self-report [Brief Symptom Inventory (BSI)] Method: The measures were completed with 109 adults who have ID and with someone who knows them well. Results: Level of agreement across the four scales in common was good for three. The poorest convergence was for the obsessive compulsive disorder sub-scales. However, a high level of concordance was found between most sub-scales. Conclusion: The BSI and the PASSAD seem to be good indicators of psychiatric problems and psychological distress; however, similar to other multi-trait measures they did not demonstrate appropriate specificity for particular disorders.