Anne Boutet de Monvel, Iryna Egorova, and Gerald Teschl Inverse Scattering Theory for One-Dimensional Schroedinger Operators with Steplike Periodic Potentials (105K, LaTeX2e) ABSTRACT. We develop direct and inverse scattering theory for one-dimensional Schr\"odinger operators with steplike potentials which are asymptotically close to different finite-gap periodic potentials on different half-axes. We give a complete characterization of the scattering data, which allow unique solvability of the inverse scattering problem in the class of perturbations with finite second moment.