Presented here is an argument for the existence of universals. Like Church's translation- test argument, the argument turns on considerations from intensional logic. But whereas Church's argument turns on the fine-grained informational content of intensional sentences, this argument turns on the distinctive logical features of 'that'-clauses embedded within modal contexts. And unlike Church's argument, this argument applies against truth-conditions nominalism and also against conceptualism and in re realism. So if the argument is successful, it serves as a defense of full ante rem realism. The argument emphasizes the need for a unified treatment of intensional statements -- modal statements as well as statements of assertion and belief. The larger philosophical moral will be that ante rem universals are uniquely suited to carry a certain kind of modal information. Linguistic entities, mind-dependent universals, and instance-dependent universals are incapable of serving that function.