The contribution of computer simulation studies to our understanding of the prop erties of a wide range of condensed matter systems is now weIl established. The Center for Simulational Physics of the University of Georgia has been hosting a series of annual workshops with the intent of bringing together experienced prac titioners in the field, as weIl as relative newcomers, to provide a forum for the exchange of ideas and recent results. This year's workshop, the third in the series, was held February 12-16, 1990. These proceedings are arecord of the workshop and are published with the goal of timely dissemination of the papers to a wider audience. The proceedings are divided into four parts. The first contains invited pa pers dealing with simulational studies of classical systems and also includes an introduction to some new simulation techniques. Aseparate section is devoted to invited papers on quantum systems, including new results for strongly correlated electron and quantum spin models believed to be important for the description of high-Tc superconductors. The third part consists of a single invited paper, which presents a comprehensive treatment of issues associated with high perfor mance computing, including differences in architectures and a discussion of access strategies. The contributed papers constitute the final part.