Conventional wisdom holds that landed elites oppose democratization. Whether they fear rising wages, labor mobility or land redistribution, landowners have historically repressed agricultural workers and sustained autocracy. What might change landowning elites' preferences for dictatorship and reduce their opposition to democracy? Change requires reducing landowners' need to maintain political control over labor. This transition occurs when mechanization reduces the demand for agricultural workers, eliminating the need for labor-repressive policies. We explain how the adoption of labor-saving technology in agriculture alters landowners' political preferences for different regimes, so that the more mechanized the agricultural sector, the more likely is democracy to emerge and survive. Our theoretical argument offers a parsimonious revision to Moore's thesis that applies to the global transformation of agriculture since his Social Origins first appeared, and results from our cross-national statistical analyses strongly suggest that a positive relationship between agricultural mechanization and democracy does in fact exist.