The present paper critically examines two different approaches to metonymy, one based on contiguity and another one based on domain inclusion. The defendants of the former (Dirven 1993; Warren 1999; Blank 1999) describe metonymy in terms of the relations of conceptual contiguity existing between two domains. On the other hand, authors like Lakoff and Johnson (1980), Lakoff and Turner (1989) or Ruiz de Mendoza (1999) define metonymy as a relation of inclusion between two cognitive domains, the matrix domain and its primary or secondary subdomain. The main criticism leveled against the first approach concerns its incomplete classifications of metonymy whereas the critics of the second one claim that the notions of inclusion and centrality are subjective (cf. Feyaerts 1999).