In genre research and discourse analysis studies dealing with relationships between texts of different genres tend to have one of two foci: Either demonstrating structural relations between genres in the form of purpose, situation or linguistic/non-linguistic features, or demonstrating transformational relations between individual texts from different genres under the broader heading of "popularisation". Less attention has been devoted to what we call the "derivational relationship" between written texts from different genres. This may be due to the fact that in order to determine that a text is derived from another text or to establish what aspects of the text have been derived, one must gain control over external variables that are not easily controllable. In our approach, we suggest a method that - while controlling external variables - is designed to isolate a suitable text corpus. Contrary to other recent studies within the field of relationships between texts from different genres, our rather strict delimitation of a corpus allows us to describe the sort of textual relationship where we say that one text belonging to one genre is not merely related to but in fact derived from another text belonging to another genre. In this article we call this relation "inter-generic derivation" (IGD). The article presents an empirically oriented case study of inter-generic derivation.