OBJECTIVE: Little consensus exists regarding the relationship between socioeconomic status (SES) and substance use. This study examined the associations of three indicators of family SES during childhood–income, wealth, and parental education–with smoking, alcohol use, and marijuana use during young adulthood. METHOD: Data were obtained from the national Panel Study of Income Dynamics, a survey of U.S. families that incorporates data from parents and their children. In 2005 and 2007, the Panel Study of Income Dynamics was supplemented with two waves of Transition into Adulthood data drawn from a national sample of young adults, 18-23 years old. Data from the young adults (N = 1,203; 66.1% White; 51.5% female) on their current use of alcohol, cigarettes, and marijuana were used as outcome variables in logistic regressions. Socioeconomic background was calculated from parental reports of education, wealth, and income during the respondent's childhood (birth through age 17 years). RESULTS: Smoking in young adulthood was associated with lower childhood family SES, although the association was explained by demographic and social role covariates. Alcohol use and marijuana use in young adulthood were associated with higher childhood family SES, even after controlling for covariates. CONCLUSIONS: Findings based on three indicators of family background SES–income, wealth, and parental education–converged in describing unique patterns for smoking and for alcohol and marijuana use among young adults, although functional relationships across SES measures varied. Young adults with the highest family background SES were most prone to alcohol and marijuana use.