Background: Chronic pain is a critical healthcare challenge for VA, and older Veterans are affected worst. VA guidelines emphasize psychological treatments as first-line for chronic pain. Yet available psychological options in VA, including Cognitive-Behavioral Therapy for Chronic Pain (CBT-CP) and Mindfulness Meditation (MM), produce only modest and time-limited benefits on average and are thus underutilized. To increase effectiveness and uptake, VHA experts have recommended (1) testing treatments with potentially larger and more durable benefits, such as [MM that is tailored for chronic pain] and Emotional Awareness and Expression Therapy (EAET), a unique approach that addresses emotional and relational processes not directly addressed by CBT-CP or MM; (2) testing group and video telehealth delivered treatments to improve access; (3) identifying mechanisms of response so that future treatments can target the most powerful mechanisms; and (4) determining moderators of response to promote treatment matching. A large-scale trial directly comparing telehealth-presented group EAET, CBT-CP, and MM tailored for chronic pain among older Veterans can address all these recommendations. Significance: The proposed randomized clinical trial directly compares EAET, CBT-CP, and MM, each delivered in groups over video telehealth, an important format to promote access and scalability. In performing lagged analyses of mechanisms, the trial will also generate comprehensive results on how psychological pain treatments work, including whether EAET, CBT-CP, and MM work through unique mechanisms based on their respective conceptual models or via shared mechanisms. In evaluating important demographic variables and other moderators that are mechanistically linked to each treatment, we will also learn how to optimize benefits and maximize limited resources by selecting the most appropriate Veterans for each treatment. Innovation & Impact: The trial focuses on older Veterans, an important but understudied group of chronic pain patients. In addition, the trial's direct effectiveness comparison of multiple active interventions to each other is quite rare but allows for sophisticated analyses of mechanisms and moderators. Indeed, the trial uses innovative lagged analyses of mechanisms collected at multiple time points, whereas most other studies only evaluate whether pre-post changes of mechanisms correlate with pre-post changes in outcomes. Finally, the study aims to be performed entirely remotely to increase the impact of findings. Overall, results are expected to impact clinical practice and guidelines within VA. Specific Aims: Test whether there are differences in outcomes among the three treatments, whether EAET is superior to CBT-CP and MM, and whether MM is superior to CBT-CP. Test whether potentially unique mechanisms precede and predict improvements in those assigned to the relevant treatment and potential shared mechanisms precede changes in outcomes across indivi...