There is a consistent trend towards miniaturization of deviees and systems in many fields of engineering, in order to achieve significant reductions in size, weight, power consumption and cost. This trend is especially evident in optics and optoelectronics, where recent years have seen rapid growth in such new or renewed areas as rnicrooptics, integrated optics, integrated optoelectronics, and diffractive optics. In November 1996, an international group of scientists convened in Eriee, Sicily, for a meeting on the subject of "Diffractive Opties and Optieal Mierosystems." This Conference was the 20th Course of the International School of Quantum Electronies, under the auspices of the "Ettore Majorana Center for Scientific Culture" and was directed by Prof. Franeo Gori of the Third University of Rome, Italy, and Prof. Giancarlo Righini of the "Nello Carrara" Institute of Research on Electromagnetic Waves (IROE-CNR) in Florence, Italy. This book presents the Proceedings of this Conference, providing a fundamental introduction to the topie as weIlas reports on recent research results.