Through a critical exposition of the essential literature on the concept of “subject” in Danish it is demonstrated that the subject properties which are put forward there — and which are related to different levels of description: phonology, morphology, syntax, semantics — are mutually incongruous. We argue that it is only possible to define the subject as a collection of features drawn from several levels. On the basis of the feature collection which we postulate the problem “subject as sentence constituent” is incorporated into the valency model, and in this connection a distinction is made between the abstract valency-conditioned entity and its realization in given sentence patterns. Sentence constituents are entities which can be defined only for sentence patterns.