In this paper, we describe the systems of complex adpositions in modern Romance languages, and discuss their status and definition. We do so with a corpus-based analysis focusing on three Romance languages, French, Portuguese and Romanian, and show that some features of complex adpositions are common to most if not all varieties, while some seem to be specificities of one or more of these languages. One case in point is the way such constructions can be tested, for instance with possessives-a test which does not seem to affect French and Portuguese (Catalan, etc.) CAs in the same way: the clear contrast found in French between non-lexicalized constructions and CAs on account of their intolerance of the possessive is not to be found in Portuguese. Finally, we formulate a hypothesis as to the development of CAs in various Romance languages, suggesting it may not have been parallel.