Toxicogenomics is a discipline that combines expertise in toxicology, genetics, molecular biology, and environmental health to help understand the response of living organisms to stressful environments. The National Research Council convened a workshop to discuss how toxicogenomic data could be applied to improve risk assessments, particularly cancer risk from environmental exposure to chemicals. Risk assessments serve as the basis of many public-health decisions in environmental, occupational, and consumer protection from chemicals. The workshop provided a forum for communities of experts, including those working in -omics and those in the policy arena, to discuss where their fields intersect, and how toxicogenomics could address critical knowledge gaps in risk assessments.