Adults with predominantly severe and profound mental retardation (N = 180) who lived in a developmental center were assessed with the Behavior Problems Inventory and the Diagnostic Assessment for the Severely Handicapped-II. Individuals with self-injurious, stereotyped, or aggressive/destructive behavior had generally higher psychopathology scores than individuals without, and the presence of behavior problems increased the likelihood of almost all psychiatric conditions up to three-fold. Factor analysis revealed that behavior problems tended to be associated with psychiatric conditions conventionally linked with behavior problems. A Self-Injury and Aggression/Destruction factor was related to impulse control and conduct problems, and a Stereotyped Behavior factor was linked to pervasive developmental disabilities and somewhat less so to schizophrenia. Stereotyped Behavior factor was independent of the Self-Injury/Aggression/Destruction factor.