Vaikhanasa (वैखानस) or Vaikhanasagama (वैखानसागम) is a tradition of Hinduism that primarily worships Vishnu (and his associated avatars) as the Supreme God. The tradition draws its name from the philosophy propounded by its founder, Sage Vikhanasa. Vaikhanasa is classified as a Vaishnava Agama, concerned with the performance of practices such as temple rituals. Its adherents are primarily the Brahmins who belong to the school of the Krishna Yajurveda Taittiriya Shakha and the Vaikhanasa Kalpasutra. It is principally monotheistic in its philosophy, whilst also incorporating elements that could be described as being panentheistic. Like the Pancharatra and Shaiva Agama tradition, it traces its origin to South India. The Vaikhanasas originated as a group of forest-dwelling ascetics. In the Manava Dharmashastra, the legendary Manu discusses the vanaprastha, forest-dweller, the third of the four ashrama stages of life, and mentions a "Vaikhanasa rule." Other ancient authorities support this reference, so it seems there was a Vaikhanasa ascetic community before the common era. They are mentioned in the Narayaniyam, which is a late section of the Mahabharata of uncertain date but probably no earlier than the third century CE. Surviving Vaikhanasa sutras are no older than the fourth century CE. Inscriptions from perhaps the eighth century CE identify Vaikhanasas as temple priests, and from the end of the tenth century they are prominently mentioned in South Indian inscriptions. Vaikhanasas were the priests of Vishnu temples, trusted with administering the temples and their lands. Ramanuja, a leader of the Sri Vaishnava school, attempted to replace the Vaikhanasa system of worship which came into practice with the Pancharatra system, to which he belonged. Today, Vaikhanasas are the chief priests in more than half of the Vaishnava temples in the South Indian states of Tamil Nadu, Andhra Pradesh, and parts of Karnataka. Their present-day temple activities are worthy of attention, as are their efforts to work for community integrity which is threatened by increasing social and technological changes.