During the Second Republic of Spain (1931-1939) and within the framework of ambitious social reform, the government of the "Generalitat" of Catalonia launched a social and educational assistance system. This new system would be independent, modern, and capable of surpassing the traditional welfare system based on religious charity that was predominant in Spain at the time. One of the initiatives performed to obtain funding consisted of the sale of Christmas seals, whose earnings would be allocated to the fight against childhood tuberculosis. The "Segell Pro Infància" organisation was created for this purpose. This article analyses the origins of this institution within the socio-political context of Catalonia during the Second Republic and the Spanish Civil War, in addition to its work and activities during its brief existence. The series of actions financed by "Segell" were primarily directed at improving institutions that provided a social welfare system, such as crèches and nursery schools. In this analysis, the commitment of early twentieth-century Catalan nationalism to social and educational modernisation, in addition to its development of social justice policies, is revealed. This reform fits into the framework of a broader pro-sovereignty project in which Catalonia would build state structures independent of Spain.