The control of optical modes by periodic dielectric structures and microcavities many believe will provide the performance improvements required for the next generation of light emitting diodes, semiconductor lasers and displays. This volume brings together reviews of microcavity physics, studies of novel two and three-dimensional photonic bandgap materials, and quantum optical studies of strong coupling between the cavity mode and various light emitters. The broad coverage provides a reference text suitable for graduate students and researchers in the field of optical and solid state physics. This volume comprises the proceedings of the NATO Advanced Study Institute on "Quantum Optics in Wave length Scale Structures", that took place in Cargese, Corsica, between August 26-September 2, 1995.