Mortality in a population of more than 1,300 people with mental retardation who live in the community was studied utilizing a case-by-case review and sentinel health event methodology. Death was noted in 14 people over a 4-year period. Cause of death was identified as avoidable (3 patients), potentially avoidable (3), unavoidable (3), sudden unexplained death with a history of epilepsy (3), or other unexplained deaths (2). Factors influencing mortality and the delivery of health care services were described. The sentinel health event methodology and case-by-case mortality reviews are recommended for monitoring avoidable deaths in community residential settings for people with mental retardation.