This book challenges the long-held theory that the English pronouns they, their, them are loanwords from Old Norse, arguing instead that the pronouns ultimately derive from the Old English demonstratives þa – þara – þam. Based on the most comprehensive quantitative and qualitative analysis yet published of third-person plural personal pronoun usage in early English, the study presents evidence of morphosyntactic and phonological continuity from Old to Middle English, particularly in the northern and (south)western dialects. It concludes that contact with Old Norse primarily reinforced existing native developments rather than introducing entirely new forms, thus highlighting the complex interplay of internal linguistic evolution and language contact that combined to shape they, their, them. This book will be of interest to students and scholars of Historical Linguistics, Language Variation and Change, Language Contact, as well as readers interested in the history of the English language.