One of the most controversial figures in Colombian history is that of Jorge Eliecer Gaitan, whose assassination of April 9, 1948, ended a twenty-year career in national politics.1 The Colombian writer-diplomat, Juan Lozano Y Lozano, has distinguished Gaitan as the man most responsible for creating a "new mood: in twentieth century Colombian politics.2 Essentially, this "new mood" is that of increased interest in national social problems which, during the lifetime of Gaitan, was accompanied by an increasing demand on the part of the masses for significant participation in the political processes of the nation. The paper is divided into three chapters. The first describes the setting for the initial political activity of Gaitan: the Colombian capital, Bogota. The second is a biographical study of Gaitan. The third examines the impact of Gaitan on Bogata during his term as mayor. An epilogue briefly discusses Gaitan after his mayoralty.