This volume is a status report based on the presentations and discussions that took place during the 12th Annual Workshop on Computer Simulation Studies in Condensed Matter Physics at the Center for Simulation Physics at the University of Georgia in March 1999. It provides a broad overview of the most recent developments in the field, spanning a wide range of topical areas in simulational condensed matter physics. These areas include recent developments in simulations of classical statistical mechanics models, electronic structure calculations, quantum Monte Carlo simulations and simulations of polymers. New physical results and novel simulation and data analysis methods are presented.