One of the major thrusts in our laboratory has been an ongoing collaboration with Dr. Trudy Mackay on the functional genomics of behavior, using olfactory avoidance behavior in Drosophila melanogaster as a model system. The avoidance response to repellent odorants in Drosophila melanogaster, a response essential for survival, provides an advantageous model for exploring how ensembles of genes control odor-guided behavior. A complete understanding of the genetic architecture of this model behavior, ultimately, requires identification of all the genes involved, characterization of their interactions in shaping the phenotype at the genetic level, and identification of polymorphisms that generate phenotypic variation at the population level. Although this seems a monumental enterprise, ongoing improvements in genomic technologies are bringing the realization of this goal within reach.