Simulation and visualization technologies that have become fundamental to contemporary science, engineering, design, and medicine have made possible new ways of seeing and knowing and thereby can change the way practitioners think. This project will explore these processes as they are experienced by scientific and engineering professionals and the ways in which these new technologies reconfigure their professional identities. Five professional fields in which practitioners use simulation and visualization technologies will be examined: archaeologists working telerobotically in deep water; weapons scientists running simulations; neuroscientists imaging the brain; physical chemists analyzing nanoparticles with atomic force microscopy; and architects building in the virtual world. The methods include field interviews, oral histories, and workshops. Fundamental questions, approaches and techniques will be developed for further research and teaching. It is also expected that professional practice will be illuminated in a way that is helpful to researchers and designers in the development of ever more appropriate technologies.