In this paper we provide a conceptual approach to modelling value propositions. We argue that rigorous modelling in an ontological style could improve several aspects of business. Modelling and mapping value propositions helps better understanding the value a company wants to offer its customers and makes it communicable between various stakeholders. Using a common language (ontology) in defining a company's offering brings manager's mental models into a common form. Further, conceptually seized value propositions are comparable to the value propositions of a firm's competitors because the follow a rigid framework and make it possible to identify the competitive position of a firm's value proposition.