This course will examine the systematic ways in which semantic content changes, or is disposedto change, across time. We will be concentrating on those expressions that fall within the “functional lexicon”, rather than the “content lexicon”. One of the crucial properties of functional morphemes is that, in any given language, their inventory is limited, as opposed to the open-ended lexicon of content items. Another important property of language-specific functional expressions is that they seem to exhibit strong cross-linguistic similarities with respect to the meanings they express. The goal is to explore the diachronic movement within these relatively small functional spaces, across a variety of domains, and demonstrate that there are generalizations to be made about the underpinnings and the dynamics of such movement. We will be looking at the innovation of new functional meanings (recruitment), their entrenchment into the grammatical system (categoricalization), and their generalization over time.