The symposium UV,Blue and Green Light Emission from Semiconductor Materials was part of the European Materials research Society (E-MRS) Spring Meeting in 1996. It was arranged to bring together specialists in growth, characterization and device fabrication of materials suitable for visible and UV optoelectronic applications. The main emphasis was on the development of semiconductor diode lasers, but work was also presented on the progress of frequently doubling techniques which have an immediate application in commercial systems. The proceedings are divided into two parts, which reflect the two streams of research based on II-VI semiconductors on the one hand and III-V GaN based semiconductors on the other hand. Although these two areas are competing for the realization of practical blue laser diodes, there are many common problems, particularly with doping and also the need for suitable substrates for the growth of lattice matched structures. Contributors presented papers on the development of blue lasers, epitaxial growth, optical structural and electrical measurements and problems of compensation of dopants and laser lifetimes. The symposium Nonlinear Optical and Optoelectronics Organic Materials dealt with the development of organic molecules and polymers as potential replacements for existing materials in electronic, optoelectronics and nonlinear optical devices.