The DC-LD is a new classification system providing operationalized diagnostic criteria in recognition of lacking applicability of standard psychiatric criteria for adults with intellectual disability. This study attempts to evaluate internal consistency, inter-rater reliability and factor structure of the Psychopathology Checklists for Adults with Intellectual Disability (P-AID), a set of checklists developed from the DC-LD. The P-AID checklists comprising 10 psychiatric diagnoses and 8 types of problem behaviors were filled in by staff at community based homes for adults with intellectual disability in Western Norway. A total of 593 were returned (66%) of which 83 had two sets of checklists. Intellectual disability was administratively defined. Alpha (alpha) values for the total P-AID checklists indicating high internal consistency. The inter-rater reliability measured by ICC showed values between 0.63 and 0.88 in 8 of 10 psychopathology Checklists. Factor analysis indicated four orthogonal units measured by the P-AID. Issues regarding sensitivity and specificity are discussed. This study is the first attempt to develop and evaluate Psychopathology Checklists based on the DC-LD. The results from this study indicate the P-AID can be used in identifying mental health needs at a detailed diagnostic level.