Catchments are fundamental landscape units for understanding water quality and managing water resources. Contemporary environmental problems are being approached more than ever by stakeholders on the geographic basis of catchments, where the underlying physical, biological, and chemical science is complex. This Gordon Research Conference focuses on catchment science, exploring the interactions among hydrological, biological and geochemical processes that shape terrestrial and aquatic ecosystems. An understanding of these processes is required in order to consider responses of catchments and ecosystems to climate warming, atmospheric deposition, land use shifts, catastrophic events, and other drivers of environmental change. Participants in this conference are typically scientists (e.g., hydrologists, ecologists, biogeochemists) from colleges, universities, and government agencies around the world.