The Applied and Environmental Microbiology Gordon Research Conference is one of the longest running Gordon Conferences and has been held every two years since 1950. This conference has been a forum for the consideration of critical or even controversial issues. For example, the supposition that pathogenicity determinants derive from environmental pools of microbial genes is receiving greater support as data accumulate. The possibility that constant interaction of bacteria and eukaryotic fungi in the environment has selected for general pathogenicity factors in the bacteria is intriguing. Thus understanding the generation of microbial biodiversity through stress and gene acquisition will contribute to our concepts of pathogen development. In the past five years, the availability of the complete genome sequences of literally hundreds of microbes has brought about a revolution in applied and environmental microbiology. The fast pace of data acquisition underscores the critical role of conferences such as this one as a forum for information exchange. The long-term success of this conference is based on the fundamental importance of microorganisms to the environment and to human health both directly and indirectly. Global change, production of greenhouse gases, the cycling of naturally occurring and anthropogenic substances, remediation of materials with genotoxic potential, and manufacture of chemicals are just a few of the areas covered by the conference that have profound impact on society.