This volume connects the latest research on language acquisition across the lifespan with the explanation of language change in specific sociohistorical settings. This conversation benefits from recent advances in two areas: on the one hand, the study of how learners of various ages and in various sociolinguistic contexts acquire language variation; on the other, historical sociolinguistics as the field that focuses on the study of historical patterns of language variation and change. The overarching rationale for this interdisciplinary dialogue is that all forms of language change start and spread as the result of individual acts of acquisition throughout the speakers' lives. The thirteen chapters in this book are authored by an international group of both established and emerging scholars. They encompass theoretical overviews of specific research areas within the broader realm of the acquisition of language variation, as well as case studies applying these theoretical advances to the exploration of language change in a wide range of sociohistorical contexts in the Americas, Oceania, and Asia. This volume will be of interest to students and researchers in the area of language acquisition, language variation and language change, especially those working on interdisciplinary and crosslinguistic connections among these areas.