Until recently, the study of representation at the subnational level was hobbled by the lack of high-quality information about public opinion. The advent of new data sources, however, as well as of new methods such as multilevel regression and poststratification, has greatly enhanced scholars’ capacity to describe public opinion in states, legislative districts, cities, and other subnational units. These advances in measurement have in turn revolutionized the study of subnational representation. In this article, we summarize new approaches to the measurement of subnational opinion. We then review recent developments in the study of the role of subnational public opinion in the political process and discuss potentially fruitful avenues for future research.