David A. Stahl received his B.S. degree in Microbiology from the University of Washington, Seattle, and completed graduate studies in microbial phylogeny and evolution with Carl Woese in the Department of Microbiology at the University of Illinois, Champaign-Urbana.  Subsequent work as a postdoctoral fellow and research associate with Norman Pace, then at the National Jewish Hospital in Colorado, involved early applications of 16S rRNA-based sequence analysis to the study of natural microbial communities. In 1984 Stahl joined the faculty at the University of Illinois with appointments in Microbiology, Veterinary Medicine, and Civil Engineering.  In 1994 he moved to the Department of Civil Engineering at Northwestern University, and in 2000 returned to the University of Washington as professor in the Departments of Civil and Environmental Engineering and Microbiology. Stahl is known for his work in ecology, microbial evolution, and systematics, and received the 1999 Bergey Award and the 2006 ASM Procter & Gamble Award in Applied and Environmental Microbiology.  Dave is a fellow in the American Academy of Microbiology and a member of the National Academy of Engineering.  His main research interests surround the biogeochemistry of nitrogen and sulfur and the microbial communities that sustain the associated nutrient cycles. Stahl’s laboratory was first to culture ammonia-oxidizing Archaea, a group believed to be the key mediators of this process in the nitrogen cycle. He has taught several courses in environmental microbiology, was one of the co-founding editors of the journal Environmental Microbiology, and has served on many advisory committees. Outside the lab, Dave enjoys bicycling, spending time with family, hiking, reading a good science fiction book, and with his wife Lin renovating an old farmhouse on Bainbridge Island.