We created an externalizing disorder composite based on DSM-IV alcohol dependence and abuse criteria, DSM-IV illicit drug (cocaine, marijuana, sedatives, stimulants, opiates, and other drugs) dependence and abuse criteria, and antisocial behavior criteria (measured with DSM-IV or DSM-III-R antisocial personality disorder or conduct disorder criteria, depending on age). Criterion counts were obtained from the reliable (kappas for individual diagnoses range from 0.70 - 0.90) and valid Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) (for those 18 years of age or older) or the adolescent version of the SSAGA (for those between 12-17) (Bucholz et al., 1994; Hesselbrock, Easton, Bucholz, Schuckit, & Hesselbrock, 1999). We did not include ADHD given the mixed literature on the genetic epidemiology of ADHD vis a vis other externalizing disorders (Young et al., 2000). Antisocial behavior was measured using criterion counts for DSM-IV antisocial personality disorder (ASPD) or ASPD DSM-III-R criteria modified to match ASPD DSM-IV criteria. Because ASPD is only assessed in those 18 years and older, DSM-III-R or DSM-IV conduct disorder (CD) criteria were substituted for those under 18. Because ASPD and CD
