This is a multi-university project to establish a coordinated research program on the effective design and use of computers in physics instruction. The project has three major components: (1) Extension and refinement of an instructional theory grounded in the view that the development of validated mathematical models for physical phenomena is the main activity of physics. (2) Application of the theory to the design of a versatile Modeling Workstation for computer-based instruction. (3) Development of techniques for using computers to enhance instruction in large classes and integrate this with laboratory instruction. The workstation will be equally applicable to classroom and laboratory instruction as well as to independent use by individual students.