Recently, the psychological construct mindfulness has received a great deal of attention. The majority of research has focused on clinical studies to evaluate the efficacy of mindfulness-based interventions. This line of research has led to promising data suggesting mindfulness-based interventions are effective for treatment of both psychological and physical symptoms. However, an equally important direction for future research is to investigate questions concerning mechanisms of action underlying mindfulness-based interventions. This theoretical paper proposes a model of mindfulness, in an effort to elucidate potential mechanisms to explain how mindfulness affects positive change. Potential implications and future directions for the empirical study of mechanisms involved in mindfulness are addressed. © 2005 Wiley Periodicals, Inc. J Clin Psychol 62: 373–386, 2006.