Abstract: “The Spanish Question: Migration, Identity, and Settler Politics in French Algeria, 1830-1939” examines the place and influence of Spanish immigrants and their French-naturalized descendants (néos) in shaping – and being shaped by – French Algeria’s evolving social, political, and racial order. Focusing on the period from France’s occupation of Algeria in 1830 through the interwar era, it demonstrates how Spanish settlers served as a vital labor force and a persistent source of anxiety for both colonial administrators and established French settlers (Français d’origine). Although formally integrated via naturalization legislation, the néos remained subject to suspicion and marginalization, prompting them to navigate a precarious “in-between” status that reveals larger tensions underlying France’s colonial vision of citizenship, politics, whiteness, and social hierarchies. Through a multi-archival approach – encompassing French governmental records, Spanish consular correspondence, press publications, and select personal testimonies – this dissertation investigates the mechanisms by which néos were both included and excluded and their responses. It shows how transnational networks, local patronage, and governmental debates and anxieties around nationality, citizenship, and identity intersected. Neither wholly imposed upon, nor wholly powerful, Spanish immigrants and néos navigated a precarious terrain of partial acceptance and lingering suspicion, forging alliances and adopting strategies that at times reinforced and at other times subverted the colonial status quo. Simultaneously, French officials, journalists, and settler elites policed and perpetuated ethnic boundaries, insisting upon distinctions between “pure” and “paper” French people in the colony. These internal settler divisions, generally overshadowed by the stark divide between Europeans and Indigenous Algerians, represent a critical but underexplored dimension of colonial Algerian history. By weaving together immigration histories, diplomatic and governmental correspondence, municipal politics, and local reporting, the study illuminates how the néos leveraged limited resources and social capital to negotiate shifting political landscapes. Across the decades in question, patterns of inclusion and exclusion were further entangled with broader changes in the French Empire, including the rise of republican egalitarian ideals, the rhetoric of “Pan-Latin” solidarity, and heightened global anxieties about communism, fascism, and other transnational ideologies. As public debates on colonial citizenship intensified, the néos confronted ongoing challenges to their legitimacy and, in turn, influenced local realignments, especially with the extreme right, that shaped Algerian settler politics. Ultimately, this dissertation demonstrates that Spanish settlers in Algeria played a pivotal and revealing role in exposing the fragility of French assimilationist frameworks. While naturalization nominally expanded the ranks of “white” citizens in Algeria, it also exposed fractures within the settler community itself, creating new arenas for social conflict and political competition. By tracing these developments, “The Spanish Question” speaks to broader historiographical conversations on the fluid boundaries of European settler identity and the complexities of colonial rule, offering a counter-narrative that goes beyond a simple colonizer-colonized binary. In so doing, it not only situates Spanish migration within the larger story of French Algeria but also enriches our understanding of how competing notions of race, belonging, and governance evolved and were contested in an empire that never fully resolved its own contradictions.