In this paper, we deal with the word class of the Danish comparative word som 'as, like'. In contrast to most previous work, we propose that som should be analyzed as a preposition rather than as a subordinating conjunction. We first present the definitions of prepositions and subordinating conjunctions that we subscribe to. Subsequently, we point out that som is plausibly a preposition because it may substitute prepositions without any significant change of meaning. We then formulate five syntactic tests which support the idea that som is a preposition rather than a subordinating conjunction. If this analysis is correct, it has consequences for the prescriptive work with which Dansk Sprognaevn (the Danish Language Council) is engaged.