This request for a Small Grant for Exploratory Research proposes an initial series of studies for the development of an implicit solvent model (ISM) for use with molecular dynamics and Monte Carlo simulations on large molecular systems. The objective of the proposed ISM is to incorporate the description of bulk solvent effects and an accounting of the macromolecule's microenvironment into the empirical potential function describing the system. With the increase in compute-power and the availability of many different simulation algorithms, it becomes possible to attempt simulations on biological systems of the realistic size. However, these simulations must include satisfactory consideration of the solvent environment in practicable computing times. The proposed ISM should achieve this goal by eliminating the need to include a large number of explicit solvent molecules in the simulated system.