“[H]is eye went neuer off of hir”

This study traces the development of off of since its origin and argues that the sequence has undergone grammaticalization into a complex preposition indicating source. The complex preposition, used mostly with transitive and intransitive verbs, imposes a motion reading upon the whole predicate. The use of the preposition is considered a feature of nonstandard PDE and it dates back to the 15th century. It is more widespread in the US but it is a BrE phenomenon carried over to the US in the course of the colonization. The study looks into BrE data up till the end of the 17th century, at which point the focus switches to AmE. It is shown that the origins of the complex preposition lie in a transparent concatenation of the telic particle off and the source preposition of. This concatenation is reanalyzed as a complex preposition. The effects of the reanalysis are most clearly visible in the AmE data beginning with the 19th century.