Social entrepreneurship (SE) involves identifying and exploiting opportunities to create social value through commercial and market-based activities. It is increasingly recognized as an important approach to addressing societal challenges that are not yet adequately tackled by existing governments, nonprofit organizations, or companies. While SE is recognized as a multilevel phenomenon involving diverse actors and processes across various levels of analysis, its explanation and effects remain only partially understood. To achieve a more comprehensive understanding of the multilevel nature of SE, I adopted a multilevel framework in this thesis to explore the various cross-level effects between macro- and microlevels on SE and its social impact. Therefore, the main research question in this PhD thesis is: How do macrolevel conditions relate to microlevel antecedents in affecting SE and its outcomes? I primarily leveraged institutional theory as the theoretical foundation to answer this research question. Overall, in this dissertation, which includes four studies reported in Chapters 2-5, I examined how institutional theory is applied in the SE domain, how macro- and microlevel antecedents jointly influence SE, and how social enterprises work with local communities to create social impact. Specifically, Chapter 2 contributes to both SE and institutional theory literature by providing an up-to-date overview of institutional theory-based SE research and discussing the ethics of SE within this research topic. It reveals three unique conversations between SE and institutions: institutional and societal change, institutional complexity and hybrid organizations, and the institutional context of SE. We further delved into each conversation, identifying new avenues for future research. We also encouraged scholars to critically examine ethics in institutional SE research and proposed several opportunities for incorporating ethics in future studies. In chapters 3 and 4, we focused on the macro-to-micro situational mechanisms in the context of SE, seeking to understand how national conditions and individual-level factors both independently and jointly predict individuals’ SE activity. Chapter 3 adopts the view of institutions as constraints and employs discovery theory of opportunities to comprehend individuals’ engagement in SE. Moving on to Chapter 4, we used the legitimacy and organizational ecology perspectives to investigate individuals’ SE behavior. These two chapters advance knowledge of SE phenomena in an explicit multilevel setting. Chapter 5 addresses recent calls for more attention to the societal impact created by SEs through the involvement of local communities. We explored what specific dynamic capabilities are needed for social enterprises to involve local communities in creating societal impact within the Chinese context. This chapter enriches our understanding of how SE fosters societal impact through community involvement, particularly in the context of China. Overall, with the above research into SE and its effects, I hope to contribute to a society where SE plays a more significant role in generating lasting change in social, cultural, and environmental issues. By gaining a deeper understanding of the multilevel nature of SE, we can craft effective policies to support the development of SE, such as encouraging the legal registration of social enterprises in different countries.