The thesis asserting the mental dependence of institutional entities is particularly debated in social ontology. One of its implications is the infallibility thesis, according to which the existence of institutional entities requires that some of their properties be known. What are these properties? After presenting the Searlian conception of institutional entities and the kind of mental dependence they manifest, I specify the content of the infallibility thesis. I then show that these properties are the deontic powers associated with these entities, (...) and that the mental attitude towards deontic powers must take the form of practical knowledge. Finally, I show that this interpretation is compatible with the existence of at least some naturalized institutional entities. (shrink)