My principle research interests are in the theory of turbulence and transport in fusion plasmas. The research has involved the development of large scale computer simulation codes. Most recently I have developed a physically comprehensive global gyrokinetic turbulent transport simulation code GYRO. Other aspects of this work have dealt with providing a physical basis for empirical tokamak confinement time scaling laws and with transport code simulations of tokamak experiments. In particular I developed the concept of projecting dimensionally similar discharges to ignition, ExB shear stabilization rules, and the physically comprehensive gyrofluid transport model GLF23 now used at many tokamak laboratories worldwide.