In December 2021, the new collective volume edited by Elena Seoane and Douglas Biber came out in the Benjamins' series Studies in Corpus Linguistics: Corpus-based Approaches to Register Variation. As the first collective volume to focus exclusively on corpus-based approaches to register variation, the chapters herein provide an exhaustive account of the range and depth of possibilities that the vast domain of register variation in English has to offer. They illustrate register variation analysis in different theoretical frameworks, such as Probabilistic Grammar, Systemic Functional Linguistics, Information Theory, and propose a new framework within the Text Linguistic Approach, the continuous-situational analytical framework. Many of the contributions apply Multi-Dimensional Analysis to corpus data in order to unveil register (dis)similarities, while others rely on logistic regression models and periodization techniques based on Kullback-Leibler divergence. The volume includes both inter-register and intra-register variation in British and American English, in a wide range of L2 varieties, in learner varieties and in EFL, and also contains diachronic studies covering early and late Modern English. Such a broad scope should be a source of inspiration for anyone interested in historical and ongoing register variation in a vast range of varieties of English worldwide.