The constituents of many abundant elements on the Earth, including those composing our own bodies, are manufactured during the brief explosion stage of a massive star known as a supernova. The Principal Investigator proposes to continue his theoretical work on the advanced stages of evolution of stars, including several aspects of supernova explosion. His previous work has been pivotal in the past to an understanding of the explosion of the Supernova 1987a from a blue supergiant progenitor. The continuation of his study will focus on providing the astronomical community with evolutionary models of stellar structure, of improving the physics of semiconvection and diffusion on which these models have been based, on treating the explosion of a supernova as a problem in the well-understood context of stellar winds, and on improving the "rapid"-process rates of nucleosynthetic reactions.