The set of prepositions in Dutch can be divided in two classes, for which the terms type A and type B are used. The complement of a type A preposition can be stranded when its complement takes a special form (e.g. er achter 'there behind', waar in 'where in'), but this is not possible with type B prepositions (e. g. *er namens 'there in name of', *waar gedurende 'where during'). The two classes show a wide range of additional differences with respect to frequency, register, morphology, interpretation, transitivity. It is argued that only type A prepositions are real prepositions, that is, members of category P. Type B prepositions are syntactically complex, consisting of two heads: a preposition and a member of another category, a noun (e.g. middels 'by means of' or benoorden 'north of'), a verb (e.g. betreffende 'concerning' or behoudens 'barring'), an adjective (e.g. inclusief 'including'), or even a preposition (e.g. beneden 'beneath'). The prepositional head is often realized as a prefix (be-) or affix (-s). The impossibility of stranding type B prepositions can be made to follow from locality constraints on movement