Mindfulness in the West is often described as a bare attentional process, but it is unclear how such attention regulates emotional arousal to promote well-being. One hypothesis suggests that mindfulness involves “turning towards” experience: Through curiosity, openness, and acceptance, emotional experience is enhanced, and this attentional enhancement obviates the need for other conditioned responses. An alternative hypothesis is that mindfulness involves “turning down” experience, rapidly recognizing emotional perturbations and countering them with a relaxation response. In a neuroimaging study, we compared a Mindfulness-Based Stress Reduction (MBSR) intervention against a Progressive Muscle Relaxation (PMR) active control condition. Relative to PMR, mindfulness training more powerfully increased emotional acceptance, increasing rather than suppressing emotional processing in the brain, and better improving the ability to resist emotional distractors in our experimental task. These findings support the characterization of mindfulness as “turning towards” experience, suggesting that mindfulness and relaxation are effective but distinct regulatory strategies.