This volume contains contributions based on the lectures delivered at the Third In ternational Workshop on Nonlinear Dynamics and Quantum Phenomena in Opti cal Systems, which was held in Blanes, Girona, Spain, 1-3 October 1990. Blanes is a charming small town located on the well-known Costa Brava. With the con venient facilities of the Centre for Advanced Studies (CEAB), Blanes followed of the previous meetings of this series, which were held at Palma the tradition de Mallorca and Santander. We aimed to provide an opportunity for scientists active in the broad field of quantum optics to meet in an informal atmosphere, thus promoting the ex change of ideas and allowing a search for interconnections between seemingly unrelated topics and a cross fertilization of the different subfields of quantum optics. We encouraged contributions dealing with the newest and most important developments in quantum optics. The main topics included instabilities, chaos, spatiotemporal dynamics, and pattern formation in lasers and nonlinear optical devices; phase dynamics; generation and detection of squeezed and other non classical states of light; coherent interaction of light with atomic systems; and multiphoton processes and above-threshold ionization. The meeting brought together a group of 72 optical scientists from Belgium, France, Germany, Israel, Italy, Spain, the United Kingdom, USA, and USSR. In the technical program, nine invited papers were included, presented by eight distinguished specialists."