BACKGROUND: Recent advances in the treatment of multiple myeloma (MM) have been associated with improved survival, predominantly among young and white patients. The authors hypothesized that sociodemographic factors, adjusted for race/ethnicity, influence the survival of younger patients with MM. METHODS: Overall survival (OS) data were obtained for individuals included in the Surveillance, Epidemiology, and End Results (SEER-18) program who were diagnosed with MM before the age of 65 years between 2007 and 2012. The sociodemographic variables addressed were marital status, insurance status, median household income, and educational achievement in the county of residence. Race/ethnicity was defined as a self-reported construct including Hispanic (regardless of race), non-Hispanic black, non-Hispanic white, and other. RESULTS: There were 10,161 cases of MM included with a median follow-up of 27 months (range, 0-71 months; 22,179 person-years). Using multivariable Cox proportional hazards analysis, SEER registry; age; male sex; and 3 sociodemographic factors including marital status (other than married), insurance status (uninsured or Medicaid), and county-level income (lowest 2 quartiles), but not race/ethnicity, were found to be associated with an increased risk of death. The 4-year estimated OS rate was 71.1%, 63.2%, 53.4%, and 46.5% (P<.001), respectively, for patients with 0, 1, 2, or 3 adverse sociodemographic factors. Hispanic and non-Hispanic black individuals were found to have more adverse sociodemographic factors and worse OS. However, when the population was stratified by the cumulative number of sociodemographic factors, no consistent association between race/ethnicity and OS was observed after adjustment for confounders. CONCLUSIONS: Sociodemographic factors that potentially affect care, but not race/ethnicity, were found to influence the survival of younger patients with MM. Cancer 2016;122:3183–90. © 2016 American Cancer Society.