This study investigates the causes of the Iranian revolution of 1978-79. To this end, the different theories of revolution are reviewed in Chapter One. Chapter Two provides a discussion of the historical background of the country and the role the clergy played in shaping its political development. Socioeconomic and political factors which contributed to the outbreak of this revolution are examined in the following two chapters. Finally, an attempt is made to draw some conclusions on whether existing theories of revolution can fully explain the Iranian upheaval of 1978-79 or not. For the preparation of this study United States government documents and Iranian and English language scholarly works were consulted.