This thesis is in the form of a literature review of the theories advanced by both academics and revolutionaries of why and how a revolution occurs. The thesis is in two parts: the first part describes theories devised by academics to explain why revolutions occur. These theories are divided into three categories based on the level of analysis chosen by the academic. The second half of the thesis deals with the organizational choices made by revolutionaries. These choices amount to the development of a theory, not always explicit, on how revolutions occur. I divide the field into those revolutionaries who choose centralized versus decentralized organizational forms, and those who rely on mass movements versus those who concentrate on actions by elites. The major conclusions of the thesis are that no single level of analysis is sufficient to explain why revolutions occur, and that the choices of organizational form have more to do with the structural considerations of the environment than the will or wishes of the revolutionaries. I end with a call for more research on the organizational choices of revolutionary movements.