At its meeting in Porto, Portugal, in November 2009, the Main Commission of the International Commission on Radiological Protection (ICRP) approved the formation of a new Task Group, reporting to Committee 4, to develop guidance on radiological protection against radon exposure. This article describes the Task Group's draft report entitled " Radiological Protection against Radon Exposure" which has been posted on the ICRP website for public consultation between January and June 2012. In this report, the Commission provides updated guidance on radiological protection against radon exposure. The report was developed considering the recently consolidated ICRP general recommendations, the new scientific knowledge about radon risk, and the experience gained by many organisations and countries in the control of radon exposure. The report describes the characteristics of radon exposure, covering sources and transfer mechanisms, nature of the risk, exposure conditions, similarities with other existing exposure situations, and challenges to manage radon exposure. In order to control radon exposure, the Commission recommends an integrated approach that is focused as much as possible on the management of the building or location in which radon exposure occurs, regardless of the purpose of the building and the category of the occupants. This approach is based on the optimisation principle, and a graded approach according to the degree of responsibilities at stake, notably in workplaces, and the level of ambition of the national authorities. The report emphasises the importance of preventive actions, and provides recommendations on how to control radon exposure in workplaces when workers' exposure can reasonably be regarded as being the responsibility of the operating management. In such a case, workers' exposures are considered to be occupational, and are controlled using the corresponding requirements on the basis of the optimisation principle, and application, as appropriate, of the dose limit. © 2012.