Adolescents with alcohol-related problems often also use cigarettes and marijuana. Furthermore, early childhood characteristics that increase the risk for adolescent alcohol use disorders also increase the risk for problematic drug use. Identifying these characteristics early in childhood can be important for the prevention of alcohol and other drug (AOD) use disorders. As a result, researchers are seeking to identify liability factors and observable characteristics (i.e., phenotypes) that can predict substance use disorders (SUDs) across drug categories. Other studies are focusing on endophenotypes--characteristics that cannot be openly observed but which link a person's genetic makeup, or genotype, and disease. Both predictive behavioral phenotypes and endophenotypes may reveal pathways connecting heritable predispositions and early environmental influences to later SUDs. One suggested predictive phenotype is psychological dysregulation, which is characterized by cognitive, behavioral, and emotional difficulties in childhood. An endophenotype that has been studied extensively is a particular brain wave called the P300 event-related potential. For people who are at high risk of AOD use based on these characteristics, adverse environmental conditions frequently lead to SUDs. Given the strong evidence that childhood psychological dysregulation predicts problematic AOD use, effective interventions for preventing adolescent SUDs may need to target the environmental features that put adolescents with this behavioral constellation at increased risk.