This research program has the primary goal of microscopic prediction and explanation of the properties of strongly interacting quantum many-body systems crossing several disciplinary boundaries but with an emphasis on nuclear many-body problems. Some activities and expected results include the study of high-momentum nucleons in nuclear ground states by applying Green's function techniques to quantitative prediction of the (e,e'p) cross section. A corresponding study will assess the potential of two-proton removal experiments as a probe of the nucleon-nucleon interaction in the nuclear medium. Calculations involving self-consistent determination of nuclear-matter spectral functions will establish the density dependence of medium modifications of nucleons and their effective interactions and generate in-medium phase shifts and cross sections relevant to the analysis of heavy-ion collisions. Fundamental features of pairing by predominantly repulsive interactions will be studied in the framework of a new separation transformation of the gap equation. Correlated basis functions (CBF) calculations of superfluid pairing gaps in neutron-star matter will furnish critical inputs for models of the rotational dynamics and thermal evolution of neutron stars. Variational-CBF and correlated density matrix theories adapted to inhomogeneous environments will be applied to pairing in non-uniform nuclear systems, resonant vapor modes of the helium liquid-vapor interface, Bose-Einstein condensation phenomena in trapped atomic clouds, and phase transitions in lattice spin systems and lattice gauge models.