Previous research has suggested substantial variation in prevalence rates of psychiatric disorders in individuals with intellectual disability (ID) and also differential patterns of associations between psychiatric disorders and challenging behaviors in people with ID. The aim of this study was to determine the prevalence rate of specific psychiatric disorders and challenging behaviors and the relationship between them in a community-based sample of individuals with ID. A community-based sample of 159 adults primarily with mild and moderate ID was surveyed for the presence of psychiatric disorders and challenging behaviors using the Behavior Problem Inventory and the Psychiatric Assessment Schedule (PAS-ADD). Individuals who met threshold on the PAS-ADD were subsequently evaluated using the Mini PAS-ADD Interview. Screening for psychiatric disorders using the PAS-ADD indicated a prevalence rate of 10%. There was a large discrepancy between the overall rate of challenging behaviors (45%) and the rate of psychiatric disorders identified by the Mini PAS-ADD Interview (6%). However, the rate of more severe behavior problems (8%) was closer to the rate of psychiatric disorders (6%). Thirty-one percent of people with severe challenging behaviors also were rated as having psychiatric disorders and odd ratio analysis indicates that individuals with severe challenging behaviors are substantially more likely to present with a psychiatric disorder. However, the relationship between different topographies of challenging behaviors and discrete diagnostic categories of psychiatric disorders appears to be unclear. This study reports a low prevalence of psychiatric disorders in a community-based population. The presence of severe challenging behaviors appears to have some association with psychiatric disorders but does not appear specific to discrete diagnostic categories. Clinicians and researchers need to debate the validity of considering challenging behaviors atypical manifestations of psychiatric disorders. (Contains 1 figure and 1 table.)