The grammars of living languages are constantly changing, never so obviously than when we compare different stages of a language over a long period of time: words change form and are sometimes repurposed; new words enter and others are lost; morphology rises and falls; syntactic possibilities can change dramatically. How do such changes arise, and what does it mean for a language to change? The aim of this course is to introduce students to the field of diachronic linguistics: its relationship to general linguistics, its primary research methods, and its major achievements. Students will gain practical experience solving classic language change problems, performing their own analyses, and reading contemporary literature in the field.