We report the results of an empirical investigation of the extent to which supernatural believers endorse a porous conception of the mind, i.e., the belief that one’s thoughts can be directly perceived by others. We developed a porous theory of mind (PToM) scale, tested its factor structure by using both exploratory and confirmatory factor analyses, and showed the relation of PToM with supernatural beliefs in three studies in the Netherlands and one study with North-American participants. We found that endorsement of a PToM is positively related to paranormal beliefs. We also showed that the endorsement of a porous view of the mind differs between people from different religious backgrounds (i.e., Protestants vs. Catholics; spiritualists vs. religious believers). The finding that supernatural believers endorse a porous conception of the mind fits well with recent work in the field of the anthropology of religion and the psychology of paranormal beliefs. We propose that our PToM scale provides a parsimonious measurement tool (i.e., consisting only of 4 items) that circumvents socially desirable responding, while providing direct insight in the endorsement of paranormal beliefs.