This Chapter contains a review of empirical studies of meditation. Included in the discussion are psychological and neurophysiological effects and correlates, EEG, and neuroimaging studies of meditation. This chapter concludes with a discussion on whether the meditative state is a unique physiological state. Studies of meditation by practitioners of yoga, Zen, and transcendental meditation (TM) suggest that meditative state is a distinct and unique state of mind and that it lowers arousal and is conducive to better health and well-being. However, considering the fact that practices of meditation vary significantly in different meditative traditions, it is difficult to pinpoint precisely what it is in meditation that is conducive for promoting health and wellness. Also, there is no compelling neurophysiological configuration which may be considered as unique to a meditative state. Empirical research shows that meditation enhances one's ability to focus attention, and attention is the key ingredient in the control of mind. Other cognitive effects of meditation include improved memory. The paranormal effects of meditation are a significant part of Patanjali's Yoga Sūtra.