Emerging adulthood has heightened risk for substance use. College students experience unique challenges, making them prone to use of alcohol, marijuana, and nonmedical use of prescription drugs. This article reviews rates of college students’ substance use, risk factors, and populations at elevated risk. Consequences include legal, academic, and mental health problems; engagement in other risky behaviors; increased rates of injury; and death. Researchers, clinicians, and university administrators must identify those at greatest risk and provide prevention and intervention programs. Despite broad evidence supporting such programs, many students fail to access appropriate treatment. Future research should elucidate treatment barriers.