Recent advances in semiconductor technology have made it possible to fabricate microcavity structures in which both photon fields and electron-hole pairs (or excitons) are confined in a small volume comparable to their wavelength. The radiative properties of the electron-hole pairs and excitons are modified owing to the drastic change in the structure of the electromagnetic-field modes. This book is the first to give a comprehensive account of the theory of semiconductor cavity quantum electrodynamics for such systems in the weak-coupling and strong-coupling regimes. The important concepts are presented, together with relevant, recent experimental results.