This paper deals with German sentential idioms of the type Da geht einem ja der Hut hoch! ('This makes one's hat go up': "This is outrageous"), Das kannst du den Hasen geben! ('Give it to the rabbits': "That is worthless"), Du hast wohl nicht mehr alle Tassen im Schrank! ('Don't you have all your cups in the cupboard any more?': "You are crazy") etc. It is argued that those sentences are instantiations of certain productive patterns of construction. As opposed to Kay (2002), the paper argues that the productivity of constructions should be accounted for by a morphological rather than a syntactic approach. That is, productivity is considered as a gradual phenomenon that has to be measured empirically. Furthermore, it is argued that productivity does not have to be contrary to idiomaticity. On the basis of a classification of German idiomatic patterns of construction, the paper examines in how far these turn out to be productive and whether there is any variation in profitability with regard to the different patterns. Two elicitation tests, one on the interpretation and one on the production of new idiomatic sentences, were carried out with 16 and 18 German native speakers as subjects respectively. As a result, the tests show that the idiomatic patterns are productive both with respect to interpretation and production.
