This chapter outlines the Buddhist origins of mindfulness meditation, its role in self-healing and liberation, and the psychological mechanisms of change that contribute to its clinical benefits. Mindfulness involves a voluntary, sustained, present-centered attention, which resists automatic habits of thought, emotion, and action, facilitating discernment and transformative insight. Some researchers refer to a subset of Buddhist thought and practice as a contemplative science, because the Buddha based his teaching on a causal theory of mind and well-being. The four foundations or foci of mindfulness taught within the meditative pedagogy are: the body, sensations, mind, and realities. One review of the clinical research on mindfulness identified five major mechanisms underlying positive change: relaxation, acceptance, affect tolerance, behavior change, and meta-cognitive awareness/insight. When a client trains in mindfulness of breath, or any similar concentrative technique, s/he will usually experience decreased arousal and a sense of calm and relaxation. Several Buddhist doctrines elucidate the principles of karma theory.