Objectives: We estimated the societal costs imposed by and the relative contributions of risky driving, drinking–driving, and substance use among young adults visiting a large urban emergency department who exhibited both high-risk driving and problem drinking. Methods: Emergency department patients aged 18 to 44 who screened positive for risky driving and problem drinking (n = 275) were surveyed regarding driving behaviors, substance use, injuries, work absences, health care utilization, legal problems, and traffic crashes over the previous year. These data, supplemented by police crash reports, were used to estimate costs. Univariate and multivariate regressions tested for associations between costs (logarithmically transformed) and risky driving, drinking–driving, and substance use. Results: Societal costs related to driving behavior and substance use averaged $19 342 per person, annually. One in 4 individuals had experienced a mild or moderate injury in the prior year, but no one in our sample had been involved with a severe injury or fatality. One in 5 had been in a crash in the prior year. Risky driving was significantly associated with higher health care costs in multivariate models and with total costs in univariate and multivariate models. Alcohol use was associated with increased injury and crash costs. Drinking–driving was not associated with increased costs in multivariate models but was associated with reduced health care costs. A one standard deviation increase in risky driving was associated with increased health care costs of $159 and increased total costs of $1306 per person, annually. Conclusions: Risky driving imposes significant costs, even controlling for substance use and drinking–driving. Interventions to reduce risky driving may be cost-saving to society.