Although previous research demonstrates that clinical individuals with delusions score low on one of the facets of cognitive insight, self-reflection, and high on the other facet, self-certainty, analogous studies of delusion proneness in nonclinical individuals have found that delusion proneness in nonclinical individuals associates with higher levels of both self-certainty and self-reflection. The present study sought to reconcile these inconsistent results by examining the contributions of different facets of self-reflection, rumination and reflection, to delusion proneness. One hundred fifty-two individuals completed three questionnaires: the Beck Cognitive Insight Scale (BCIS), the Peters et al. Delusions Inventory (PDI), and the Rumination-Reflection Questionnaire (RRQ). The results showed that the individuals scoring higher on delusion proneness demonstrated higher levels of both self-certainty and self-reflection on the BCIS as well as higher levels of rumination and reflection on the RRQ. As predicted, the strength of the relationship between BCIS self-reflection and delusion proneness was diminished when rumination was controlled for. These findings suggest that the previously observed positive relation between BCIS self-reflection and nonclinical delusion proneness might be driven, in part, by the ruminative aspect of self-reflection.