Merrell, WillieWe describe the use of superspace techniques to discuss some of the issues in string theory. First we use superspace techniques to derive the effective action for the 10D N=1 Heterotic string perturbatively to first order in the parameter alpha prime. Next we demonstrate how to use the superspace description of the supersymmetric gauge multiplet for chiral superfield in 2d N=(2,2) to discuss T duality for sigma models that realizes a particular case of generalized Kahler geometry. We find that the salient features of T duality are captured but at the cost of introducing unwanted fields in dual sigma model. Fortunately the extra fields decouple from the relevant fields under consideration. This leads us to introduce a new supersymmetric gauge multiplet that will eliminate the need to introduce extra fields in the dual sigma model.en-USDissertationPhysics, Elementary Particles and High EnergyMathematicsT DualityGeneralized Kahler Geometry