This is a group proposal in computational high energy physics to be carried out by the MILC Collaboration. This research addresses fundamental questions in high energy and nuclear physics, and is directly related to major experimental programs in these fields. It requires very large scale numerical calculations that are widely recognized as one of the grand challenges of computational science. The human resources proposed here will enable us to attack several crucial new physics issues. These include (1) a study of the electromagnetic effects and nonperturbative mass renormalization needed to obtain a precise determination of the masses of the light quarks (2) a new high-precision theoretical determination of the nucleon mass (3) a determination of mixing parameters for the B and K mesons needed to fix fundamental constants in nature and (4) a study of the thermodynamics of the quark-gluon plasma at nonzero nuclear density. These initiatives require the development of new application codes within the MILC framework, the running of those codes, and the detailed analysis of the output to extract the relevant physical results. This project supports the needed postdoctoral research associates to carry this work to fruition.