The paper aims at providing an expanded model of grammaticalization, where the term is understood as the process through which a language develops grammatical means of coding various formal, semantic or pragmatic functional domains. It thus subsumes the traditional scope of grammaticalization, but also covers the development of devices such as linear order, phonological means and the repetition of phrases or lexical items, among others. In this expanded scenario of grammaticalization, the paper addresses such key issues as the motivations for grammaticalization, the choice of coding means, and the consequences of grammaticalization for grammatical systems and for language change. The article also discusses the relevance of the principle of functional transparency, the principle of indirect means and the consequences of the initial state for both principles.