Introducing a collection of papers on suppletion looked at from a diachronic angle, this paper surveys questions that have been asked (or should be) and answers that have been considered, in this issue and elsewhere, about how, why, where, and when suppletion originates, with particular lexical items and morphological categories; what happens to suppletion once and as long as it is there; how, why, where, and when suppletion disappears again; and how suppletion fits with particular approaches to morphology and general theories of language.