This article seeks to showcase the previously underexplored theoretical potential of the recent “sub-national turn” in comparative politics. Specifically, I hope to delineate how theories derived to explain variation in an outcome across sub-national units can enrich our repertoire of theories to explain variation in the same and/or related outcomes across national units. I show the potential of this method of theory generation through an analysis of social welfare, a specially apposite outcome for this purpose because it has been studied rigorously at the both the national and sub-national levels of analyses. I argue that sub-national analyses can, on the one hand, help us refine and rethink national-level theories for the same outcomes. They can push us to nuance and extend established national theories and show us how the same variables and mechanisms that have been hypothesized to explain cross-country variations might work differently, even in opposite directions, within countries. On the other hand, sub-national analyses can push us past the established repertoire of national-level explanations to bring to light new (or forgotten) theories. In this way, this article seeks to challenge cross-country analyses as the exclusive domain of theory building in comparative politics.