How do new patterns emerge in languages? This question has been subject to a great deal of theoretical speculation but the focus of our course will be empirical, looking at actual cases. We will begin with recent research on exceptions to established patterns. Next we will tackle the diachronic question of how large-scale borrowing of complex words leads to productive patterns, concentrating on the Latinate element in English. Here we have the advantage of large amounts of data over a long period. Again from English, we will look at the gradual organization of the writing system over a millennium. In the second half of the course we will turn to the emergence of sign languages. We first discuss how sign languages emerge, focusing on two types of sign language emergence: in Deaf communities and in village (rural) communities. We then discuss the emergence of three phenomena: the emergence of consistent word order in young sign languages and in spontaneous gestural systems invented in the lab; the emergence of verb agreement by recruiting space for referent-tracking purposes; and the emergence and expansion of the lexicon in young languages, focusing on compounding and new derivational affixes.