Tufts/CfA/MIT Cosmology Seminar, at MIT: Tom Banks, Rutgers University Title: Modular Cosmology Abstract: I discuss the virtues and problems of an approach to inflationary cosmology in which the inflaton fields are the moduli of string theory. This leads to interesting insights about the cosmological constant, supersymmetry breaking, and the physical mechanisms which might determine the choice of the vacuum state in superstring theory.