Modern agriculture would be impossible without chemical fertilizers produced from phosphate rock. The global rise of input-heavy farming practices in the nineteenth and twentieth centuries depended on access to phosphate-based fertilizers. In 1896, fifteen years after France established a protectorate in Tunisia, rich phosphate deposits were discovered in Tunisia’s Gafsa region. The phosphate industry quickly became France’s most important colonial interest in Tunisia. It utterly transformed the Gafsa region, left an indelible mark on Tunisian nationalism and decolonization, and fueled agricultural production in Europe and around the globe. This paper documents the role of Gafsa’s workers and their families in the new networks of capital that developed as Tunisia’s economy was reoriented to prioritize phosphate exports. I argue that modern Tunisia was indelibly shaped by the social and economic networks that emerged with the phosphate industry, and these networks cannot be understood without accounting for the agency of workers and their families. I draw on previously unexplored documents from the Gafsa Phosphate Company archives, as well as colonial and post-independence administrative records, military documents, maps, and hospital records housed in both Tunisia and France. From the rise of the phosphate industry in the late 1890s to the French-owned mining company’s gradual nationalization in the 1960s and 1970s, I chart how Gafsa’s workers negotiated with and resisted against local authorities. Specifically, I explore how workers’ actions posed fundamental problems for Tunisia’s urban nationalist elite by revealing fragmentation within a nationalist movement that posited unity, and I examine how workers’ demands created dilemmas for the mining company as it navigated the changing circumstances of the global phosphate market. This paper challenges the dominant paradigm of both Tunisian nationalist and Western historiography, in which Tunisia’s urban coasts drive historical change while Gafsa (along with other rural regions) is passively marginalized. By centering the narrative around Gafsa’s workers and situating them within the networks of capital that developed from the export of phosphates, I argue instead that Tunisia’s integration into late-nineteenth-century and twentieth-century global capitalist markets developed as a multi-actor process in which Gafsa’s workers and their families were active participants. Concurrently, these networks caution us against taking Tunisia for granted as a national unit. Not only do they highlight disunities that the Tunisian nationalist movement has tried to elide, but they also reveal the drawbacks of assuming that Tunisia’s 1956 independence is a rupture point.