Background: Jumping to conclusions (JTC) is a reasoning bias in which persons arrive at conclusions with relatively little data. It is prevalent in schizophrenia and tied to outcomes. To understand the correlates and the roots of this phenomenon, this study explored whether deficits in mastery, a domain of metacognition which reflects the ability to use knowledge about oneself and others to cope with psychological problems, was linked to a heightened tendency to jump to conclusions. Sampling and Methods: Participants were 40 adults with a schizophrenia spectrum disorder in a nonacute phase being treated in an outpatient setting. JTC was assessed using the Beads Test, and mastery was measured as an element of metacognition using the Metacognition Assessment Scale. To rule out the possibility that results were the effect of impairments in memory or executive function, the Wisconsin Card Sorting Test and Hopkins Verbal Learning Test were included. Results: Partial correlations controlling for memory and executive function revealed that lower levels of mastery were correlated with a lower average number of beads requested before reaching a conclusion, or a greater tendency to jump to conclusions (r = 0.39, p < 0.05). Conclusions: Results are consistent with the possibility that deficits in metacognition influence or are influenced by reasoning biases.