In 1853, the director of the Belgium Royal Observatory, Adolphe Quetelet, welcomed delegates from several countries to two consecutive meetings that have acquired considerable reputation as the first international congresses of, respectively, meteorology and statistics. This paper examines the local context where several similar international congresses (on free trade, universal peace, prison reform, public hygiene, etc.) were organized in the same decade. It argues that the new Belgian state developed this new form of international conference in order to bolster its soft power in the Concert of Nations. It also discusses tensions between national interests and global beliefs in the efficiency of science, which arose from these congresses.