We provide scientific and technical leadership in fundamental and applied theoretical research on nuclear, particle, astrophysics, and cosmology theory and simulations. The members of the Nuclear, Particle, Astrophysics and Cosmology Group in the Theoretical Division also contribute and collaborate beyond these core disciplines as opportunities arise. The group maintains theory, modeling and simulation capabilities in a broad set of areas. Current activities in the group include research in the Beyond the Standard Model grand challenge, Lattice QCD, RHICILHC physics, nonequilibrium field theory, gravitation and gravitational waves, precision cosmology, dark matter and dark energy, neutrino physics, astroparticle physics, high energy astrophysics, cosmology and galaxy formation, plasma astrophysics, proto-planet formation and migration, astrophysical data analysis and processing, nuclear many-body theory and nuclear astrophysics, nuclear reaction theory, fission, and nuclear data evaluation, processing and validation testing for applications that include stockpile stewardship, threat reduction, and energy security.