Theory provides a conceptual framework by which to comprehend a series of events. It allows linkages to be drawn between the present and the past while simultaneously enabling predictions regarding the future. Often when explaining a certain event or era, multiple theories exist; some may be compatible, others may not, but usually and most importantly, no one theory is able to elucidate all aspects of these events. No one theory is either mutually exclusive or collectively exhaustive. Historical interpretation is highly dependent upon the framework adopted to investigate a particular phenomenon. In other words, the theory conditions the evaluation by allowing only certain variables to come under the scope, only certain questions to be asked.

Given the parameters of theory, it is often helpful to evaluate how distinct social movement theories account for the same historical event. Divergent understandings derive from the different questions that are asked. This chapter offers a brief overview of various social movement theories including the classical approach, rational choice, resource mobilization, new social movement, and political opportunity structure.