The so-called periphrastic constructions found in Spanish, and the problems which they pose for linguistic description and classification, provide a useful vehicle for exploring the possibilities for combining synchrony and diachrony. This book centres on an examination of one such construction: tener + past participle. A detailed study of this often neglected construction is justified in its own right, but in addition, because it is of uncertain grammatical status, it encapsulates many of the problems encountered by the synchronic linguist. The work focuses on a study of tener + past participle as used in the modern language, and a historical survey of its evolution. The interplay between the two is set against the background of various existing theories concerning auxiliary and periphrastic verbs, providing detailed data against which such theories can be tested. It also places the development of tener + past participle within the wider context of similar developments in other Romance languages.