This paper is the result of one working group in a workshop entitled "An Agenda for Human-Computer Interaction Research: Science and Engineering Serving Human Needs." The workshop, sponsored by the National Science Foundation, brought together "20-25 of the most prominent HCI researchers from the disciplines of computer science, engineering, information science, psychology, and human factors along with several NSF staff members." The workshop results, to appear in the HCI literature, identify critical research issues and potential avenues for assaulting them, along with necessary infrastructure recommendations related to educational, professional, and facility problems. The overall topical area was divided into five areas, each with an individual researcher in charge of directing discussion and reporting on the area. The areas included theory and taxonomy of HCI models, the interface development process, I/O devices and interaction styles, software tools, and computer supported collaborative work.