Distress tolerance, or the ability to withstand uncomfortable states, is thought to be a transdiagnostic risk factor for psychopathology. Distress tolerance is typically measured using self-report questionnaires or behavioral tasks, both of which construe distress tolerance as a trait and downplay the potential variability in distress tolerance across time and situation. The aim of the current study was to provide a method for assessing momentary distress tolerance using ecological momentary assessment to capture both within- and between-individual information. Participants (n = 86) responded to random prompts on their cell phones seven times per day for one week, which included 10 momentary distress tolerance items as well as momentary emotion. After examining item distributions and interclass correlations, we conducted a multilevel exploratory factor analysis using both within-individual and between-individual data to arrive at a brief, 3-item measure we call the Momentary Distress Intolerance Scale. Model fit and reliability indices were good for both within- and between-individual approaches. We found that distress tolerance varied significantly over time, and that average momentary distress intolerance and instability in momentary distress intolerance were associated with trait distress tolerance, emotion dysregulation and tendencies to use experiential avoidance. Neither average momentary distress intolerance nor instability in momentary distress intolerance correlated with behavioral distress tolerance tasks. We discuss the importance of construing distress tolerance from a dynamic perspective and provide recommendations toward future research.