From the perspective of ecology, metabolism determines the rate of exchange of energy and materials with the environment, and the rate of allocation of these resources to all components of the life history: maintenance, growth and reproduction. From the perspective of evolution, metabolic rate determines underlying processes that govern rates of molecular evolution, rates of speciation and extinction, and patterns in species diversity. This Gordon Conference will bring together a highly diverse set of researchers from both sets of perspectives who are working at the forefront of the field of metabolic ecology. These participants will represent a variety of complementary disciplines and approaches. We will include physiological, biomechanical, and evolutionary viewpoints; and the invited speakers will present research ranging upwards in physical scale from the molecular level, to single cells, to multicellular organisms, to entire ecosystems. Our intent is to create a conference environment that will attract the brightest and most interactive members of the scientific community to a unique, open forum that will identify and solve new problems in metabolic ecology. The ultimate goal of this meeting is to foster new collaborative interactions that will help us to move towards a more complete understanding of the metabolic laws that govern the structure and function of living organisms, and the communities and ecosystems in which they reside. We believe that each participant in the 2004 Gordon Conference at Bates went back to their home institutions with at least one new idea to explore, or one new hypothesis to test. These ideas and developments will stimulate the growth and evolution of the field of metabolic ecology, and will also create a new knowledge base for future Gordon Conferences.