PURPOSE: This investigation examines the relationship between socioeconomic status (SES) and melanoma incidence in counties included in the Surveillance, Epidemiology, and End Results Registry (SEER) in the United States from 1973 to 1993. METHODS: Cases included whites, aged at least 15 years, with a morphologic diagnosis of malignant melanoma, residing in one of 199 counties at the time of diagnosis. County level measures of SES including median household income, percentage of high school graduates, and percentage of families below poverty were abstracted from the 1950, 1960, 1970, 1980, and 1990 U.S. Census data. The relationship between SES factors and melanoma rates was examined by hierarchical Poisson regression. RESULTS: The percentage of high school graduates was significantly and positively associated with the incidence of melanoma (relative risk (RR), 1.28; 95% confidence interval (CI), 1.21-1.35), after controlling for age at diagnosis, gender, time period, latitude, and percentage of Hispanics in the county. Percentage of families below poverty was significantly inversely associated with the incidence of melanoma (RR, 0.66; 95% CI, 0.55-0.78). When education and poverty were included in the same model, both the positive effects of education (RR, 1.23; 95% CI, 1.16-1.31) and the negative effects of poverty (RR, 0.85; 95% CI, 0.74-0.98) persisted. In contrast, median household income was not associated with melanoma incidence in a similar multivariable model (RR, 1.00; 95% CI, 0.99-1.00). CONCLUSION: Whether the effect of education on incidence of melanoma reflects lifestyle behaviors that modify exposure to sunlight or some other factor remains unclear. Nonetheless, the findings of this study suggest that the determinant is primarily related to education, not income.