String topology (Chas-Sullivan, Cohen, Jones,...) studies the homology of the loop space of a manifold by exploiting the what are known as string operations. With the goal of producing an equivariant version of the theory, we formulate string topology for topological stacks and prove the existence of string operations under certain natural hypotheses. As a consequence, we obtain equivariant string topology for compact Lie group actions on manifolds. This is a joint work with K. Behrend, G. Ginot, and P. Xu.