This article summarizes a symposium that was organized by Dr. Kim Fromme and presented at the 2003 annual meeting of the Research Society on Alcoholism in Ft. Lauderdale, Florida. The four presentations illustrate the emerging technologies and methods that are now being used to investigate the genetic basis of differential sensitivity to alcohol and their behavioral manifestations. Combining human genotyping with laboratory measures of behavior and subjective reports, these presentations represent state-of-the-art approaches to crossing the bridge from the Decade of the Brain to the Decade of Behavior. Dr. De Wit's paper describes her research on the neurobiological basis for individual differences in sensitivity to the stimulant and sedative effects of alcohol. Evidence suggests that activity of the dopaminergic and GABAergic neurotransmitters underlie these stimulant and sedative effects, respectively. Both Drs. Hutchison's and Corbin's papers describe their research on polymorphisms for the serotonin transporter (SLC6A4) as a determinant of the subjective effects of alcohol challenge. Dr. Hutchinson's and Ms. Ray's findings indicate that individuals with the short form of the SLC6A4 alleles (S) demonstrated a low level of response to alcohol, thus supporting previous research that the S allele may be associated with increased risk for alcohol dependence. In contrast, Dr. Corbin did not find a reliable association between the SLC6A4 genotype and subjective response to alcohol. Mr. Cook's and Dr. Wall's paper adds another dimension to this article by presenting research on both the aldehyde dehydrogenase (ALDH2) and alcohol dehydrogenase (ADH2) genetic variants and their association with the alcohol-related flushing response that is prevalent in Asian populations. Dr. David Goldman provides concluding remarks.