The National Cancer Institute Initiative in Chemical Genetics is designed to encourage the development of small molecular probes. The probes are useful for activating or inactivating protein functions, thereby providing resources that help discern the functions of gene products in normal and disease cells, as well as in tissues. This initiative includes "ChemBank," a suite of informatics tools and databases aimed at promoting the development and use of chemical genetics by scientists worldwide. The information generated with such tools should provide a critical link from genomic discovery to drug development.