BACKGROUND: In Australia, diagnosis and management of depression in adults with intellectual disability (ID) often occurs within the primary care setting. Few tools are available to assist general practitioners (GPs) in the diagnostic process. The study aim was to assess properties of carer and GP checklists developed to address this problem. METHOD: Participants were 49 adults with ID and their paid carers (support workers), and GPs for 27 adults. Data from carer and GP checklists were gathered, in addition to carer completed Developmental Behaviour Checklist-Adults (DBC-A). Adults with ID also received a comprehensive psychiatric assessment. RESULTS: Both checklists demonstrated good internal consistency (KRS-20 = 0.90). A factor analysis of the carer checklist indicated a single factor on which three section totals had loadings of greater than 0.722 (depressed mood, loss of interest, and social interaction and communication). This factor was interpreted to be depression. The GP checklist data were insufficient for factor analysis, but section totals were moderately correlated with most corresponding carer checklist section totals. Carer section totals related to depression also correlated highly with the DBC-A Depression sub-scale, demonstrating good concurrent validity. Contrasting results were obtained for the GP checklist. Most (n = 42) of the participants were diagnosed with a psychiatric disorder, precluding the testing of checklist specificity and sensitivity. CONCLUSION: The carer checklist shows promise as a means of gathering information needed by a GP in the diagnosis of depression in adults with ID. Further research into its underlying properties and clinical uses of a combined depression checklist is warranted.