The U.S. Global Change Research Program was established in 1990 to develop scientific projections of anticipated impacts of the changing biosphere on humans and social systems. As part of this program, the National Science Foundation created the Arctic System Science Program (ARCSS). This document describes the ARCSS Human Dimensions of the Arctic System (HARC) initiative to consider how humans interact with physical and biological environmental change in the Arctic. HARC cuts across traditional social, biological, and physical science disciplines; employs varied methodologies; collects data across a broad range of time and spatial scales; and involves local people and communities in research design and implementation. Five fundamental research questions address the impacts of human activity on arctic and global systems; types and sources of global change in the Arctic; effects of global changes on human societies in the Arctic; alternative approaches to current and future problems; and effects of arctic changes on people living outside the region. Ethical research issues include informed consent by individuals and communities, community involvement in research, the use and distribution of traditional indigenous knowledge, and intellectual property rights. HARC includes funding and guidelines for linking research with science education in arctic community schools. (Contains 51 references, other relevant publications, reviewers and participants in a related workshop, and photographs). (SV)