As we describe in this chapter, most psychological disorders invok e a fundamental problem w ith inflexibility, lack of insight, or narrow ed perspective—that is, mindlessness. Recent advances in psychological science, neuroscience, and mindfulness research suggest that mindfulness training can target a variety of mindless mental processes that cut across numerous psychological disorders. These common processes specifically include negative affectivity and emotional reactivity, repetitive negative thinking such as rumination, experiential avoidance, attentional bias, reappraisal, and suppression of thoughts and feelings. Because these repetitive, inflexible, distress-producing ways of thinking, perceiving, and behaving are implicated in many disorders (e.g., anxiety, depression, posttraumatic stress, substance use, sleep disturbance, eating disorders, and chronic pain conditions), such mental processes have been coined “transdiagnostic”, literally meaning across illnesses. In a paradigmatic shift aw ay from conventional, disorder-specific treatment, there is a new movement toward focusing on transdiagnostic treatment approaches that target a core set of psychopathological processes that seem to underlie many clinical disorders. By reviewing the nature of transdiagnostic mental processes, describing their role in the etiology across psychological disorders, and demonstrating the ways in which mindfulness meditation can help through mindful learning, we propose that an integrated view of Eastern and Western mindfulness may offer a “transtherapeutic” approach to understanding optimal mind-bodv health.