Activities on the international level were for a long while dominated by the International Penitentiary Commission (IPC), founded in 1878. By World War I, about 20 countries had nominated delegates. The IPC met once a year to discuss penal problems and published a regular periodical. In 1929, the IPC changed its name to the International Penal and Penitentiary Commission (IPPC). In 1951, the United Nations took over the tasks previously performed by the IPPC and held its first Congress on the Prevention of Crime and Treatment of Offenders in 1955. Activities of the International Association of Penal Law, the IPPC, and the International Association of Criminology were supplemented by the International Society of Social Defense. These four associations have met every year since 1963 for a joint colloquy, and their collaboration remains strong and efficient. 8 footnotes.