Spiritual discipline or Yoga constitutes an inseparable part of the philosophy of every school, and especially the Tantric ones, in which spiritual practices or sadhana kriya dominate. This book opens with an account of the nature, origin and development of Saiva-Sakta Tantras, their classification under different schools, the wealth of literature available belonging to these schools, etc., and sheds light on the principal metaphysical tenets of Saiva and Sakta Tantras. The book deals also with the concepts of divine Grace or saktipata, guru and his different kinds, the process of initiation (diksa) and its varieties, mantra’s nature and place in sadhana kriya, etc. This book also attempts to remove the misconceptions wide-spread in the academic world about the theory and practice of Tantra Yoga, which have been deliberately kept secret by the practitioners to prevent their misuse by unscrupulous persons. Dr. Debabrata Sen Sharma is a well-known scholar of the Advaita Shaiva thought of Kashmir.