Current cosmological theories posit the existence of a vast ensemble of different universes, i.e., regions of space-time that evolve separately from our own. Motivated by the possibility of these other universes, this project will study the effects of different values of the fundamental constants on cosmic evolution and structure formation. The variations in the laws of physics explored here will include the strengths of the fundamental forces and the values of basic cosmological parameters. The parameter space under consideration is relatively large, but is nonetheless well-defined. This project will delineate the region of this parameter space for which complex astrophysical structures can be produced. These studies will include the synthesis of nuclei in the early universe, the formation of galaxies and large scale structure by gravitational collpase, the production of stars, the structure of stars, the possibility of non-conventional stars (such as black holes and dark matter stars), and finally planets. With these parameter studies in place, the project will conclude by defining the subset of parameters that allow universes to produce all of the structures required for complexity; this study will thus provide a consolidated view of structure formation across the multiverse. This study will focus on the existence, formation, and evolution of physical structure. However, these physical entities provide the building blocks for biological structures, so this work will have wider implications.