This is a scholarly book on one of the oldest living relgions of India. Tracing the basic tenets of Vaisnavism to the hymns of Rgveda the earliest religious literature of the world, the author has shown how an ancient cult has developed itself by successive stages into a well formulated monotheistic system in the hands of Ramanuja and his illustrious followers. In the second part of the book the fundamental philosophical theories of Visistadvaita Vedanta are presented to prove that Vaisnavism is not a mere religious cult, but has a credible philosophic foundation.