Dutch partitive constructions of the type one of the (few) X who Y show a striking pattern of singular subject-verb agreement in their relative clause. This paper presents a corpus study showing that the prescriptively “incorrect” singular agreement pattern is in fact the dominant pattern in Dutch. In order to explain this, we argue that this type of partitive construction often has a specific function in context, namely, to point out that the subject is special or extraordinary, usually for the reason presented by the relative clause. We apply a usage-based approach to this construction within the framework of Construction Grammar, arguing that the prevalent implicature of the subject’s specialness has become a conventionalized part of the meaning of the construction. This analysis then can be used to explain the syntactic pattern of singular agreement within the relative clause. A similar albeit less pronounced pattern can be found in German.*