  These lectures review some of the basic properties of $N=2$ superconformal
field theories and the corresponding topological field theories. One of my
basic aims is to show how the techniques of topological field theory can be
used to compute effective \LG potentials for perturbed $N=2$ superconformal
field theories. In particular, I will briefly discuss the application of these
ideas to $N=2$ supersymmetric quantum integrable models. (Lectures given at the
Summer School on High Energy Physics and Cosmology, Trieste, Italy, June 15th
-- July 3rd, 1992. To appear in the proceedings.)
