This paper presents the use of situation theory for scenario modelling. The concepts of situation theory are used to propose a form of scenario description in which not only the scenarios episodes, but also their contexts and their pre and postconditions are viewed as situations. Reasoning with situation theory allows the investigation of scenarios consequences and the identification of inconsistencies between what is expected and the actual effects resulting from scenarios actions. Also, building scenarios in a situation theoretical setting facilitates the parallel construction of a domain ontology.