BACKGROUND: Chronic pain is one of the most prevalent and disabling symptoms associated with multiple sclerosis (MS). Individuals with MS are interested in nonpharmacologic pain management approaches. Cognitive-behavioral therapy (CBT) is efficacious in improving MS-related pain outcomes. Mindfulness-based cognitive therapy (MBCT) is a promising, alternative approach. Little is known about moderators of these treatments' outcomes, however. This article describes the study protocol for the first randomized controlled trial comparing MBCT, CBT, and usual care and examining treatment effect moderators in individuals with chronic pain and MS. METHODS: We will conduct a single-center, randomized, single blind, parallel-group trial comparing MBCT, CBT, and usual care in adults with MS and chronic pain. Both interventions will be delivered via eight group sessions using videoconferencing technology. Primary (average pain intensity) and secondary outcomes (including pain interference, depressive symptoms, fatigue, and sleep) will be assessed pre-treatment, mid-treatment, post-treatment, and at 6-month follow up. Potential treatment moderators will be assessed pre-treatment. We hypothesize that participants randomly assigned to MBCT or CBT will report significantly greater reductions in average pain intensity than participants assigned to usual care at post-treatment (primary study endpoint) and 6-month follow up. We also hypothesize that mindfulness, pain catastrophizing, and behavioral activation pre-treatment will moderate response to both active treatments, but not response to usual care. DISCUSSION: Findings will provide important new information about the efficacy and moderators of two nonpharmacologic pain management approaches delivered using technology to overcome common barriers to treatment access. The knowledge gained may lead to better patient-treatment matching and, ultimately, better pain treatment outcomes in MS. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03782246. Registered on 20 December 2018.