Prior to entering a coalition with the ruling Alliance party at the beginning of 1973, and incorporation in the broader National Front coalition in June 1974 Parti Islam Se Malaysia (usually abbreviated to Party Islam or PAS, though until recently widely known as the Pan Malayan Islamic Party) had long been established as Malaysia's leading opposition party; within the National Front its position is second only to that of the Alliance. Nonetheless political scientists and historians have devoted little attention to this party, though they have almost uniformly condemned it for an alleged association with a most reactionary form of Malay communalism. Not surprisingly the picture that has emerged is partial and rather obscure. For example, we know little of the events surrounding the party's origins and its initial formative years: virtually all accounts of PAS begin with its successes in the 1959 national and state elections, and the few statements hazarded on its earlier history have been incomplete and factually wrong. In this article I want to clarify some of the factual confusion relating to these events, and to offer an interpretation of the various ideological forces that gave rise to the formation of this party.