The middle decades of the nineteenth century witnessed the rise of European influence in Egypt, and its consequent increased integration within the world economy, that preceded the British Occupation in 1882. A strong manifestation of the then-ongoing integration process was the strong repercussions on Egypt of the cotton boom that took place as a result of the American Civil War in 1861-65 and the subsequent shortage in the world supply of cotton. Interestingly, the boom in the cotton world market had strong effects that shaped the Egyptian economy, with its central reliance on the exportation of cotton, for almost a century. This paper examines the impact of the cotton boom on a relatively less studied phenomenon, the emergence of agricultural slavery in rural Egypt as the mode of production in cotton plantations. Prior to the cotton boom, slavery in Egypt, and the Ottoman Empire at large, was for domestic and sexual services. However, historians recently documented the rise of agricultural slavery in Egypt after the cotton boom, which was reportedly a very rare phenomenon in Islamic history. The paper has two goals: First, empirically, I employ a new and unique data source, the Egyptian individual-level census records from 1848 and 1868 that I digitized from the original manuscripts at the Egyptian Archives, and that are one of earliest pre-colonial censuses, with information on women, children, and slaves. The two censuses allow me to examine if the cotton boom indeed caused a surge in agricultural slavery via comparing the change in the slave population share in cotton plantation districts between 1848 and 1868 to the corresponding change in non-cotton-plantation districts. Second, theoretically, although agricultural slavery in Egypt was a short-lived institution that was abolished in 1877 (because of the European pressure), the Egyptian “natural experiment” may enhance our understanding of the underlying causes behind the emergence of slavery beyond the Nieboer-Domar model. In particular, it appears that international trade in cash crops may be an important determinant of slavery beyond the standard factor endowments hypothesis that emphasizes the relative abundance of land (compared to labor) as the underlying cause behind slavery.