The focus of this volume is to show how the various successful models of nuclear structure complement one another and can be realised as approximations, appropriate in different situations, to an underlying non-relativistic many-nucleon theory of nuclei. In common with the previous volume on Foundational Models, it starts with a broad survey of the relevant nuclear structure data and proceeds with two dominant themes. The first is to review the many-body theories and successful phenomenological models with collective and nucleon degrees of freedom. The second is to show how these models relate to the underlying many-nucleon shell model in its various coupling schemes.