The generation of fictional truths can sometimes be explained by a number of principles at work in games of make-believe. Most prominent and well-discussed are the Reality Principle, the Mutual Believe Principle, and the Principal of Minimal Departure. Lately, a number of scholars have suggested a Principle of Genre Convention, in order to explain certain fictional truths that cannot be explained be alludings to reality, or any versions of it. Walton has discussed a number of examples, such as the fact that a checkered table cloth in a family’s home in a silent movie means an “honest but poor” milieu. The principle of genre convention might even come into play when literary or filmic narratives are narrated in an unreliable fashion (cf. Bareis 2009 and 2010). Besides generic convention, media itself might be a source for the generation of specific fictional truths – in what could be called a Principle of Media Convention. Within the ”mechanics of generation” (Walton 1990), the aforementioned principles play an important role in explaining what fictionally is, or can be true. On the other hand, what actually fictionally is true is a question not only about principles, but is also related to Walton’s notion of ‘work world’ and ‘game world’. As scholars and interpreters of works of fiction, we want to be able to argue what we believe to be fictionally true, and theories of interpretation have to be combined with, and in accordance with, principles of generation. This raises a number of further methodological and theoretical questions, which I aim to discuss in my presentation.