How do preferences inherent in the linguistic system and extralinguistic constraints on contexts of use jointly shape the English language? Unprecedented in its critical focus on the conventional division of internal and external factors, this book provides fresh theoretical, empirical, and methodological insights into the dynamics of language variation and change, based on informative case studies written by experts in the field. It explicitly addresses theoretical and methodological questions regarding the prospects of isolating, distinguishing and integrating structurally or cognitively founded factors and constraints derived from contextual or social situations of language use.