Chapter 2 surveys the use of corpus-based language studies for investigations of grammatical change, including studies of the use of core grammatical features across historical periods, of the choice between grammatical variaants, and of lexico-grammatical change; these types of studies are illustrated with examples from the Corpus of Historical American English (COHA, Davies 012). The chapter argues for the need to pair quantitative analyses with non-linguistic or ‘situtaional’ analyses of registers over time, including the rise of social science disciplines, increasing diversification among disciplines, increasing specialization within disciplines, and even the sheer amount of scientific inquiry taking place. After briefly describing these historical developments as the basis for our corpus design, we describe the corpora that serve as the foundation for the analyses in the book, and summarize the major methods employed in those corpus-based analyses. In particular, this chapter introduces and illustrates the many grammatical features that we associate with grammatical complexity, including both phrasal and clausal complexity.