The central aim of my presentation is to study the relationship between prepositions and their prefixal counterparts in French and Dutch. In line with the studies by Amiot (2004, 2005) and by Blom (2005) among others, I claim that prepositions can undergo a grammaticalization process and this way develop into prefixes. This "prefixization" process can be described on the basis of several parameters. Contrary to prepositions, which prototypically interact with two syntactic arguments, assuming the semantic roles of trajector and landmark (e.g. Le livre est sur la table 'the book is on the table'), prefixes have scope only over the stem to which they are bound (e.g. suralimenter 'to overfeed'). Moreover, this functional opposition correlates with semantic differences: whereas prepositions are characterized by (spatial, temporal or metaphorical) relational semantics (e.g. expressing the "spatial superiority" of the trajector in relation to the landmark), a prefix often expresses aspectual and evaluative meanings (e.g. "excess" in suralimenter). In my PhD research (Van Goethem 2006) I studied the relationship between prepositions and their preverbal counterparts. This study revealed that in some cases the preverb maintains a prepositional function and meaning (e.g. L'avion survole les îles Baléares 'The plane is flying over the Balearic Islands'), while in others it acts as a true prefix (e.g. Il a surestimé ses forces 'He has overestimated his forces') and can be considered more grammaticalized. Dutch data revealed a third construction type: Dutch preverbs often derive from predicative adverbs with a formal prepositional counterpart (e.g. de soep opeten [literally] 'to eat up the soup') (cf. Blom 2005), a preverbal construction that does not exist in French. In my contribution, I would like to extend the analysis to nouns and adjectives beginning with an element corresponding to a preposition. The French preposition sur 'on, upon; over' and its Dutch counterparts op 'on, upon' and over 'over' will be taken as a ...