Mindfulness meditation is increasingly well known for therapeutic efficacy in a variety of illnesses and conditions, but its mechanism of action is still under debate in scientific circles. In this paper, we propose a hypothetical causal model that argues for the role of mindfulness in positive reappraisal coping. Positive reappraisal is a critical component of meaning-based coping that enables individuals to adapt successfully to stressful life events. Mindfulness, as a metacognitive form of awareness, involves the process of decentering, a shifting of cognitive sets that enables alternate appraisals of life events. We review the concept of positive reappraisal in transactional stress and coping theory, then describe research and traditional literature related to mindfulness and positive reappraisal, and detail the central role of mindfulness in the reappraisal process. With this understanding, we present a causal model explicating the proposed mechanism. The discussion has implications for clinical practice, suggesting how mindfulness-based integrative medicine interventions can be designed to support adaptive coping processes.