Acceptance and commitment therapy (ACT) is an evidence-based psychosocial intervention for chronic pain; however, in its present form ACT produces modest improvements in function and is no more effective than cognitive behavioral therapy (CBT), the current gold standard. This protocol paper describes the Acting with Mindfulness for Pain (AMP) protocol, which emphasizes and integrates formal mindfulness meditation practice within an ACT-based approach. This paper presents the rationale, design and methodology of an ongoing pilot randomized controlled trial (RCT) comparing AMP to CBT among Veterans with chronic pain (N = 86). Specifically, we argue that formal meditation practice is a necessary treatment component that directly targets key ACT processes which will help facilitate large treatment effects on function (e.g., general activity, social relationships, life enjoyment) among individuals with chronic pain. This study will be the first to consider formal mindfulness meditation practice as a principal treatment ingredient in the context of ACT for chronic pain. The purpose of this trial is to evaluate the feasibility of recruitment and collection of measures, and to examine preliminary treatment effects to determine the appropriateness of a subsequent full-scale RCT. This study will also explore within and between group change on primary and secondary outcomes including pain interference, pain acceptance, trait mindfulness, pain catastrophizing, values-based living, quality of life, practice adherence, and objective measures of physical activity. This study will help delineate the role of formal mindfulness practice within an ACT-based approach for chronic pain and provide preliminary data for a future fully powered RCT.