Strong coupling phase transitions in supersymmetric grand unified models

The determination of the temperature at which a grand unified model becomes strongly coupled should be based upon a physical quantity such as the screening length rather than the ad hoc condition that the opening becomes O(1). I use a recent calculation of this screening length (the inverse electric mass) to discuss some aspects of strong coupling behavior in the cosmology of supersymmetric grand unified models. Significant effects may occur in a variety of cases. An interesting possibility is that there may be a pair of confining and deconfining phase transitions at a temperature as low as the supersymmetry breaking scale (O(TeV)). I present illustrative examples for these effects. (orig.)