This chapter offers an analysis of the shifting fortunes of Latin, English and French between the mid eleventh and early thirteenth centuries, through the lens of linguistic ecology, drawing evidence from metalinguistic commentary in narrative sources, surviving texts, prosopography and onomastics and the findings of the linguistic subdiscipline of language contact. It argues for distinguishing between the period between 1066 and 1140, when the relatively high status English had enjoyed before the Norman Conquest reduced primarily at the hands of Latin, from that between 1050 and 1215, when emergence of French as a literary language, coupled with other late-twelfth-century social changes, more significantly diminished English’s importance as a written language. The chapter closes with some reflections on the factors that condition language choice in multilingual societies, rejecting a simple equation of language and identity.