The origin of Spanish entre tú y yo “between you and me”

The present study analyzes both diachronically and typologically the synchronically irregular Spanish syntagm, entre tú y yo “between you and me”, which employs the subject pronouns, tú and yo, rather than the expected prepositional pronouns, ti and mí. First, a thorough examination of Old Spanish texts reveals that the Old Spanish syntagm did indeed exhibit prepositional pronouns, i.e., OSp. entre mí & ti (a fact virtually unknown to specialists of Spanish historical grammar), thus unveiling a syntactic change from entre mí & ti > entre tú y yo. Next, the change is compared to the typologically similar ongoing change in Modern English, namely, between you and me > between you and I. It is then shown here that although the change in these languages appears, on the surface, to be an exact parallel, the origin, or cause, of the change in each language is different. Nevertheless, certain factors — including the ultimate inability of the preposition to govern the second of two conjoined elements, as well as word-order patterns of the subject pronouns — were indeed found to have played a role in the development of both entre tú y yo and between you and I.