This project takes popular organizations in mid-twentieth century Lebanon as its focus. These socio-political groupings were organized at the grassroots, made up of young men, and included scout organizations, social justice movements, student clubs and workers' associations. Employing a cultural history approach, the dissertation examines the cultural productions of these types of groups, ranging from group anthems to uniforms, letters of the rank and file to speeches of leaders. With these primary sources, it captures the cultures that took shape around five main actors in the field of street politics: the Lebanese Communist Party, the Syrian Social Nationalist Party, the Kata'ib Party, the Najjadeh Party and the Progressive Socialist Party. And as these groups condoned and committed acts of sectarian violence in the 1958 War and the Lebanese Civil War of 1975-1990, this dissertation also investigates the distinct cultures that formed around these groups during wartime. In the end, I argue that both inside and outside of moments of conflict, popular organizations cultivate and mobilize multiple, interactive identities to make sense of their actions, sectarian or otherwise. Moreover, I find that a critical site to explore these complex processes is their routine practices grounded in duty, strength and honor. Part I of the dissertation examines identity formation within these five groups, and the physical and symbolic spaces they produced in Beirut during the 1920s-1950s. Informed by Pierre Bourdieu's theories on social life, this historical background shows how organizational attempts to project uniqueness, win over recruits, and make partisan, often sectarian, claims over the whole Lebanese nation created boundaries between these groups. Also, the lives of individuals within these groups, regardless of the group's distinct vision for Lebanon, were colored by cultures of discipline and defense, working to normalize practices linked to violence. In Part II the dissertation takes up the two historical events of social mobilization and conflict in which these groups participated: the 1958 War (where the Kata'ib, once a nationalist scout group, serves as the focus for the investment in sectarianism) and the Two-Year War of 1975-1976 (where the Lebanese National Movement - specifically the Lebanese Communist Party, once a workers' association, and the Progressive Socialist Party, once a social justice movement - serve as the focus for the investment in anti-sectarian frames). First, through investigating the changing positions of these popular organizations throughout these two wars, the dissertation argues that these groups are active agents in producing sectarian violence, adding nuance to past characterizations of conflict in Lebanon. Second, by capturing the quite seamless shift towards practices of violence, it finds that the quotidian and routine also lay at the center of violence. Finally, by analyzing the textual and visual productions of these groups leading up to and during war, the dissertation finds that multiple and interacting identities, such as national, populist (i.e., fulfilling the needs of people and winning their support in a particular locality) and sect are mobilized to perform violence. Accordingly, sectarian violence, as it emerged in the mid-twentieth century, is sectarian because these groups defined it in sectarian (and antisectarian) terms, not because the violence was rooted in immutable sectarian differences. Collectively, “Winning Lebanon: Popular Organizations, Street Politics and the Emergence of Sectarian Violence in the Mid-Twentieth Century” seeks to bring the local level and the cultural into the study of conflict, and add nuance to the understanding of sectarianism and sectarian violence in Lebanon and the broader Middle East.