Islam, or what the author calls Mohammedanism, was brought to the coast of Indonesia by Arab traders over a period of centuries. Bryan Scott hopes that this article might prove to be suggestive material for the formulation of a law of contact between the Malays of Borneo and Islam. Scott plans to discuss what happened when Indonesian Islam was brought in touch with Malay Paganism and the typical jungle religion of Borneo. The author has formulated five “laws of contact” between the two peoples. The laws are: that the new religion fits in with the already existing ideals of the people, insofar as it does not enforce precepts which are antagonistic to the people’s ideals, when the new ideas offer better prospects than the people’s old religion for success and happiness under the existing conditions, insofar as the forces that bring the foreign faith also bring a change in civilization, and only if it incorporates into itself or tolerates quietly the old traditions of the people that continue to fit their life.