Background <p>Distress intolerance is a transdiagnostic risk factor featured in many psychotherapy models. Prior research has focused almost exclusively on between-person differences in trait distress intolerance, with limited attention to within-person fluctuations in state distress intolerance.</p> Methods <p>University students (N = 50) completed a baseline questionnaire and ecological momentary assessment 6&#xa0;× daily for 8 weeks. Multilevel models with momentary (state) distress intolerance as the outcome examined main and interaction effects between momentary negative affect intensity and trait distress intolerance.</p> Results <p>Variability in momentary distress intolerance ratings was moderate at both the within- and between-person levels. Only affect intensity showed a significant main effect relationship with momentary distress intolerance. The interaction effect was not significant in any model. The pattern of results did not differ substantively across models with high vs. low arousal affect.</p> Conclusions <p>Our findings bolster emerging research demonstrating that distress intolerance varies substantially within persons and correlates with more intense negative affect. Our results suggest that individuals high in trait distress intolerance do not rate equivalently intense negative emotions as more intolerable compared to individuals low in trait distress intolerance. Moreover, these relationships appear to be highly consistent across high and low arousal negative emotions.</p>