The sugar agro-industry in Cuba experienced strong growth in supply after recovering from the Cuban war of independence (1895-1898) and until the First World War. Growth was concentrated in the 1910-1914 period, thanks to prior transformations that allowed the industry to adapt to changes in demand at that time. Some of the explanatory factors have been studied in the historiography, but not labour, which was traditionally scarce. This article analyses and quantifies how growth was achieved, suggesting that it was due to a combination of variables. One of these was a larger population than what was recorded in the official census. Another was improved sanitary measures together with technological and organizational changes. High wages, immigration and family-based labour also helped increase the work force and its capacity. Even so, the volume of workers required could only be obtained by articulating the entire economy around sugar production and expanding the railroad network in the late 1910s to mobilize labourers.