Indexicality is a special kind of context-dependence. The first-person pronoun I, a paradigmatic indexical, refers to different people in different contexts, depending on who is speaking. At the same time, the pronoun I has a stable linguistic meaning, which amounts to a rule that tells us how to assign it a semantic value in any given context. This chapter discusses the features characteristic of indexicals, certain challenges that indexicality raises for semantics, and the ways in which those challenges have been met.