This monograph addresses researchers and students. It is a modern presentation of time-dependent methods for studying problems of scattering theory in classical and quantum mechanics. Particular attention is paid to long-range potentials. For a large class of interactions the existence of the asymptotic velocity and the asymptotic completeness of the wave operators is shown. The book is self-contained and explains in detail concepts that deepen the understanding. A special feature is its emphasis to show the beautiful analogy between classical and quantum scattering theory.