Within twelve months of the discovery of x rays, papers appeared in the literature reporting adverse effects from high exposure. By the time of the First World War, several countries were proposing restrictions for the exposure of radiation workers. In 1925, the first International Congress of Radiology, held in London, considered the need for a protection committee, which it established at its second Congress in Stockholm in 1928. This paper traces the history of the development, by ICRP, of its policies and the personalities involved in their development from its inception up to the modern era. The paper follows the progress from the early controls on worker doses to avoid deterministic effects, through the identification of stochastic effects to the concerns about increasing public exposure. The key features of the Recommendations made by ICRP from 1928 up to the current 1990 version are identified.