This chapter examines the methods by which the history of the English language has been studied over the last two centuries, examining the key theories and methods that have characterised the development of English historical linguistics. Recent approaches, drawing upon insights from pragmatics, sociolinguistics and corpus linguistics, form a particular focus of the chapter, demonstrating how the subject has shifted from one in which linguistic changes were identified and described, towards a methodology that attempts to explain why and how these changes occurred.