The prevalence of daily cannabis use and Cannabis Use Disorder (CUD) has increased in the United States over the past two decades. Brief, computerized harm reduction interventions that target specific high-risk CUD populations could be an efficient approach to reducing CUD. Distress intolerance, which refers to the tendency to negatively appraise and escape aversive emotional states, is a risk factor associated with stress-related cannabis use motivation and CUD severity/chronicity. Thus, a brief, accessible, low-cost intervention that reduces distress intolerance in those with CUD and elevated distress intolerance could have a significant public health impact. This proposed Stage I project aims to modify an existing two-session computerized distress tolerance intervention to optimize emotion regulation learning/generalization and test its impact on distress intolerance and cannabis use outcomes in a randomized controlled trial. Specifically, the intervention will be condensed to one-session and its imaginal exposure module will be modified to shape emotional engagement with the aim of maximizing within-session habituation, which will be signaled with a novel audio/visual cue (habituation cue). Habituation cues will then be delivered in just-in-time text message reminders triggered by naturalistic distress reported via ecological momentary assessment. After obtaining feedback on the modified Emotional Engagement Distress Tolerance Intervention in a small sample, the intervention's efficacy compared to a stringent, credible, time-matched health education control intervention will be tested in a randomized controlled trial in 80 cannabis users with CUD and high distress intolerance. To measure the intervention's mechanistic target engagement, multi-method distress intolerance assessments will be administered through four-month follow-up. To measure the intervention's impact on cannabis use, stress-related cannabis use motivation (lab stress- elicited craving and neurophysiological drug cue reactivity, ecological momentary assessment of stress-elicited cannabis use) will be assessed through the intervention period. Interviewer-assessed cannabis use frequency, CUD severity, and urinary THC metabolite concentration will be measured through 4-month follow-up. Quality of life and anxiety/depression symptoms will also be measured as secondary outcomes through 4-month follow-up. As an exploratory aim, a wristworn device will be used to measure ambulatory physiology during a portion of the intervention period to evaluate the feasibility of detecting heightened real- world distress based on objective indicators. Our central hypothesis is that, compared to a control intervention, the Emotional Engagement Distress Tolerance Intervention will produce superior reductions in multi-method assessments of distress intolerance, stress-related cannabis use motivation, disordered cannabis use, and psychosocial functioning. Successful completion of the proposed aims will (1) justify a subsequent Stage II trial, and (2) inform efforts to integrate the just-in-time habituation reminders with wearable technology in order to increase emotion regulation generalization opportunities and decrease participant report burden.