This study attempts to examine the influence of some specific Mahayana concepts on Sinhalese Buddhism. The first chapter serves as a historical backdrop to the inflow of various non-orthodox movements into Ceylon and records the continuous impact of the Mahayana on the Theravada from the earliest times. The second chapter deals with the development of the concept of the threefold bodhi and examines in some detail the way in which the goal of Ceylon Buddhism shifted from, the Theravada arahantship to the Mahayana ideal of Buddhahood. Furthermore it suggests that this new ideal was virtually absorbed into Ceylon Buddhism, The next chapter discusses the Mahayana doctrines of trikaya, vajrakaya , sunyata, karuna and prajna as adopted by Sinhalese writers without much concern for the philosophical import which these par excellence Mahayana concepts had for Mahayanists themselves. The fourth chapter is devoted to a discussion of particular emphasis given to the cult of Maitreya which was stimulated by the Mahayana. The growth of the concept of the ten Bodhisattvas and of innumerable Buddhas is also examined. The fifth chapter treats at length the worship of Mahayana Bodhisattvas. It tends to show how certain deities underwent various metamorphoses; local gods began in time to be worshipped as Mahayana gods, and Mahayana gods had lost their identity and merged with local gods. The last chapter deals with the development of the Bodhisattva ideal of kingship in Ceylon and countries in South East Asia, It also compares the nature of this cult in these countries with that which prevailed in Ceylon. It contends that the cult first developed in Ceylon and was used as an instrument for the legitimization of the king's authority. Thus it rejects the conventional view that the fall of the Khmer empire was the result of the introduction of Sinhalese Buddhism there.