Our objective was to determine how large, random samples of Americans define health. Two questions were used to ascertain concepts of health: Are you healthy? and How do you know? (What does health mean to you?) These questions were added to omnibus telephone surveys conducted with two random samples of adults from the 48 contiguous United States: one in 1995 (N = 1,000); the other in 2002 (N = 1,011). The surveys also collected demographic data. This study focuses on cases with complete data (N = 950 in 1995, N = 967 in 2002). In both survey samples, more than 92% of respondents reported that they were healthy. Four distinct conceptions of health emerged from responses to the "how do you know" question: physical, psychosocial, capacity, and control. While prevalence varied with survey year as well as respondent age and education, these four concepts were evident in both 1995 and 2002. There are four robust concepts of health in America. Ongoing attention to these concepts may enhance efforts to communicate about and improve health.