This application seeks support for a Gordon Research Conference on the Population Biology and Evolution of Microorganisms. This is a relatively new Gordon Conference. It was first held in 1986. It convenes every other year. Summer of 1987 was the second meeting, summer of 1989 will be the third. This is an interdisciplinary conference that brings together scientists from both population biology and molecular biology. A detailed description of the aims of the conference and a tentative schedule are attached.