Rising from its contemplative and spiritual traditions, the science of meditation has seen huge growth over the last 30 years. This chapter reviews the classifications, phenomenology, neural correlates, and mechanisms of meditation. Meditation classification types are still varied and largely subjective. Broader models to describe meditation practice along multidimensional parameters may improve classification in the future. Phenomenological studies are few but growing, highlighting the subjective experience and correlations to neurophysiology. Oscillatory EEG studies are not conclusive likely due to the heterogeneous nature of the meditation styles and practitioners being assessed. Neuroimaging studies find common patterns during meditation and in long-term meditators reflecting the basic similarities of meditation in general; however, mostly the patterns differ across unique meditation traditions. Research on the mechanisms of meditation, specifically attention and emotion regulation is also discussed. There is a growing body of evidence demonstrating positive benefits from meditation in some clinical populations especially for stress reduction, anxiety, depression, and pain improvement, although future research would benefit by addressing the remaining methodological and conceptual issues. Meditation research continues to grow allowing us to understand greater nuances of how meditation works and its effects.