This proposal centers around nuclear theory and its application to issues of importance in astrophysics and particle physics. Traditionally, the atomic nucleus is viewed as a system of neutrons and protons -- the nucleons. The interactions between nucleons lead to a variety of collective properties, involving neutrons and protons moving coherently. Projects to understand why many nuclei exhibit collective behavior typical of an enharmonic vibrator and to assess the role of proton-neutron collective pair correlations in nuclei near the proton drip line are proposed. Despite the enormous success of the traditional picture, there is now great interest in going one step deeper, to obtain a consistent picture of nuclei directly from the quark constituents of the nucleon. Baryon mappings have been suggested as a practical approach for realizing this goal. Several issues related to implementation of this method will be investigated, followed by detailed applications to real nuclear systems. Nuclear physics also plays an important role in efforts to extract information of fundamental importance in astrophysics. Two such applications will be considered -- a study of the response of a proposed iodine detector to solar neutrinos and a treatment of the beta decays associated with r- and p- process nucleosynthesis.