This paper presents information on the prevalence of a variety of health behaviors and health conditions on an American Indian reservation in the Plains region of the western United States. In addition, data from two non-Indian comparison groups were used to examine the extent to which differences in health status and health behaviors between Indians and non-Indians could be explained by differences in socioeconomic status. The American Indian data were from a survey conducted in 1988 during an evaluation of a local community-based health promotion program, part of the Kaiser Family Foundation's Community Health Promotion Grants Program. The comparison groups were 12 communities in California surveyed in evaluating the Community Health Promotion Grants Program and three Plains States participating in the Behavioral Risk Factor Surveillance Survey. The results show that the higher prevalences of risk-taking behavior among Indians and their poorer self-reported health status remained after adjustment for socioeconomic status. Also, among Indians, higher levels of income and education were not associated with improved self-reported health status and lower prevalence of tobacco use, as was the case with the comparison groups. The higher prevalences of risk-taking behaviors and ill health among American Indians residing on one reservation, even among those with higher socioeconomic status, suggests a need for the investigation of other social and environmental influences.