Need for closure refers to a motivated need for certainty. Jumping-to-conclusions bias refers to the gathering of minimal data when making overconfident probabilistic judgments. Both constructs have been associated independently with delusion-proneness. Fifty-eight nonclinical adults were assessed for jumping-to-conclusions bias using an experimental reasoning task, and need for closure, decisiveness concerning real-life dilemmas, and delusion-proneness using questionnaires. Delusion-proneness was associated independently with need for closure and jumping-to-conclusions bias, with no evidence of a direct relationship between the latter two. These results discount the view that need for closure motivates a jumping-to-conclusions bias, leading, in turn, to delusion-proneness. The various facets of need for closure proved to be independent; while intolerance of ambiguity correlated positively with delusion-proneness, decisiveness correlated negatively. The finding that delusion-prone individuals are more indecisive in everyday life was replicated using different scales. Delusion-proneness is associated independently with jumping-to-conclusions bias on experimental reasoning tasks, intolerance of ambiguity, and indecision concerning real-life dilemmas.