The influenza pandemic of 1918-1919 was one of the most severe recorded in Colombia. There were 1,900 deaths in the capital, Bogota. The poor and unprotected were the most affected. Care of victims was the responsibility of the Junta de Socorros, a private body. Based on different primary sources (mostly official documents, Junta de Socorros reports, newspapers, and medical journals) this article explores how the 1918 influenza pandemic altered Bogota's social dynamics, with particular attention to its impact on disease and mortality rates and to an analysis of how the city's sanitary conditions and political-institutional decisions and the reactions of different social sectors influenced the response of this human community to the pandemic.