Experiments on the Combined Release and Radiation Effects Satellite (CRRES) gathered the most comprehensive data ever taken to measure space radiation and its effects on electronic systems. The satellite operated in an 18° inclination, geosynchronous transfer orbit between 25 July 1990 and 12 October 1991. The period was characterized by two very different space environments separated by a major solar--initiated event in March 1991. Before March 1991 the near-Earth radiation environment was relatively quiet and well behaved. After the March event there was a much higher, much more dynamic radiation environment. The radiation environment and how it affected the CRRES Microelectronics Package (MEP) will be discussed.