This thesis is composed of three independent essays. In the first essay, I illustrate a process model for social entrepreneurship which is composed of four sub-stages-e.g., opportunity existence, opportunity discovery, opportunity exploitation, and opportunity appropriation. In the course of reviewing the process model, I have depicted some distinctive features of social entrepreneurship compared to commercial entrepreneurship. I argue that process perspective gives a framework for the development of a general theory of social entrepreneurship. The second essay deals with the more specific subject of social entrepreneurship motivation and start-up behaviors. In this essay, I propose the value- and affect-driven social entrepreneurship motivation and start-up behavior model. In the course of developing the model, I incorporate the attitude change model and other several psychological theories together with the entrepreneurial intention model. My model has meaning in that it is one of the earliest works that explains the mechanism of social entrepreneurship motivation and start-up behavior. The third essay empirically tests the theoretical relationships discussed in essay 2 over nascent social entrepreneurs in Korea. The results identify social-issue specific perceived meaningfulness, empathy, and the appreciation of non-monetary compensation as the good predictors of prosocial motivation for social entrepreneurship. In turn, the actual progress of social enterprise creation behaviors can be explained by the prosocial motivation, perceived ability for start-up activities, the direct effect of meaningfulness, and the indirect effect of the attitude toward being an entrepreneur. My research contributes to the social entrepreneurship motivation and behavior literature in that I successfully theorized and empirically tested the psychological mechanism of how the prosocial attitudes toward social entrepreneurship form and the paths this prosocial attitude is proceed to real actions. According to my results, social entrepreneurship is strongly based on the perceived value and empathy toward specific social problems. However, for actual social enterprise creation behavior happen, prosocial motivation should accompany with the perceived ability for entrepreneurship. My research has meaning that calls for the attention to the value and affect in entrepreneurship intention and behavior literature.