Problem behaviors of individuals who had one of three chromosome deletion disorders (5p- cri-du-chat, 15q- Prader-Willi, or 17p- Smith-Magenis) were investigated. The Aberrant Behavior Checklist was used. Results were contrasted with those of two groups of people with mental retardation who were described in other studies. The checklist rates many, but not all, potentially relevant behaviors. Eating abnormalities, known to be problematic in Prader-Willi syndrome, and sleep abnormalities, believed to be problematic in Smith-Magenis syndrome, were not included in the survey. All three disorders were associated with greater ratings of problem behaviors than the comparison groups on at least one subscale of the checklist. The results lend support to the partial specificity model of behaviors associated with genetically determined syndromes.