This study describes the prevalence of alcohol and drug use, abuse, and dependence among adults on the Texas-Mexico border in 2002-2003. The findings are based on survey responses from a random sample of 1,200 adults living in households in three communities: El Paso, a densely populated city in west Texas; the less dense urbanized areas of the lower Rio Grande Valley in south Texas; and rural or semirural colonias--unregulated settlements characterized by lack of basic public services--in south Texas. The findings revealed similarity in drug use across the three sites but higher rates of binge drinking and alcohol dependence in the colonias. Border alcohol and drug use appeared similar or lower than use among residents of Texas as a whole or Hispanics nationwide; however, problems of abuse and dependence appeared somewhat higher on the border. (Contains 2 notes and 4 tables.)