Patanjali's Yoga-Sutras are universally considered to be among the two or three most important texts in the field of yoga. Patanjali refers to his yoga as "Kriya Yoga": the "yoga of action with awareness". Until now, commentators have treated it as a philosophical reference, and have largely ignored its implications for yogic practice. They have also ignored the fact that it is also an esoteric work, and that only initiates, with sufficient prior experience, can grasp its deeper meaning. This new translation and commentary provides a practical guide to Self-realisation or enlightenment. It clearly explains how to apply Patanjali's profound philosophical teachings in everyday life, in any situation with a unique "practice" section after each verse's commentary. There is also comparison with "Thirumandiram" a classic work of the siddha tradition.