This article concerns five French prepositions that mark an inclusion relation and are ordinarily considered to be synonyms of dans ‘in’. The first is a simple preposition: parmi ‘among’. The other four are complex prepositions built from nouns of internal location (au centre de ‘at the centre of’, au milieu de ‘in the middle of’) and from names of body parts (au cœur de ‘at the heart of’ and au sein de whose word-for-word translation is ‘at the breast/bosom of’ but stands for ‘within’ ‘in’ or ‘among’ depending on the context). We will examine them from two different, yet complementary points of view. As part of a statistical approach, we use an association measure to determine the distributional trends of each preposition. In addition, we explore in greater detail the semantic mechanisms brought into play using the theoretical framework of Cognitive Grammar. This double analysis leads us to demonstrate that these prepositions are far from synonymous and involve very different types of constraints.