Michael Fisher is jointly supported by a grant from the Theoretical and Computational Chemistry Program in the Chemistry Division and the Materials Theory Program in the Division of Materials Research to continue his theoretical research in statistical mechanics, the study of ordered states of matter, phase transitions between states, and critical phenomena. The methodologies to be used include thermodynamic and scaling analyses, renormalization group methods, Monte Carlo simulations, and analytical and numerical techniques. Applications include: 1) investigations of fluid electrolytes that undergo Coulombic as opposed to solvophobic phase separation; 2) investigations of two-dimensional, hard core ionic fluids which provide a basic model for real systems exhibiting superfluidity and superconductivity; 3) the characterization of thermodynamic behavior near critical endpoints, particularly in fluid mixtures; 4) investigations of wall free energies and universal aspects of critical adsorption. Theoretical models of complex molecular systems are useful for understanding and interpreting experimental observations on these systems. They provide molecular insights into the complex molecular interactions that are responsible for macroscopic behavior and physical properties. Such insights are frequently also useful in optimizing the design of new materials having desired properties.