Vaccination yes or no? The topic of vaccinations often leads to discussions and makes many parents feel insecure. Under the motto "We inform - you decide", information seekers, e.g. parents, can use the MMR decision support tool on the BZgA (Federal Centre for Health Education) website to find out about the risks of measles, mumps and rubella and MMR vaccination, compare the risks and weigh up the arguments in favour of vaccination. In this project, the MMR decision aid will be revised according to the scientific standards of the International Patient Decision Aid Collaboration and tested experimentally in laboratory studies. Special attention will be paid to providing accurate risk information and reducing reactance, i.e. the feeling of being restricted in your decision making. The aim is to enable users to make a neutral decision process that reflects their individual preferences. The new version of the MMR decision support tool will be presented during the European Immunization Week (24th - 30th of April, 2016).