Appeals to idiom data have played an important role in arguments about the relation between English prepositional datives (Mary gave a present to John) and double object forms (Mary gave John a present).The claimed existence of idioms in both types has led researchers to conclude that the two constructions are independent, with no derivational relation between them. This article shows that the factual claims are mistaken: no English dative idioms exist in either type. Forms like give ~ the creeps/show ~ the ropes are not double object idioms because they are not idioms—they are fully compositional. Forms like throw ~ to the wolves/send ~ to the showers are not dative idioms because they are not datives—they are caused-motion constructions. The former misanalysis arises from a confusion of idioms with collocations. The latter misanalysis arises from a simplistic view about the syntax-semantics mapping, namely, that oblique datives univocally express caused motion. Given that English dative idioms do not exist, arguments about the derivational relatedness of dative forms in English must appeal to other data.