This article studies the smallpox vaccination policy from 1820 to 1840. Focusing on its implementation, it seeks to contribute to understanding this policy regarding the design and the particularities it assumed when it was taken to other regions of the country. It is postulated that in this period, the State showed its decision to formalize a vaccination program underway since the first decades of the 19th century, with resources and vaccinators specifically contracted for this purpose. Although the policy implementation presented difficulties, its most remarkable achievement was establishing the vaccination process in Chile's different provinces and departments. Among the problems that vaccination faced, one of the main ones was territorial expansion, the instability of available resources, issues with the recruitment and availability of vaccinators, and the challenge of adequately and transporting the fluid.