This study reported on mean risk magnitude judgements expressed by French participants aged 8 to 75 years , on a set of 91 hazardous activities, substances, and technologies. It then systematically analyzed the effects of age factor on the judgments. Between elderly people and young and mature adults, few notable differences were detected. The most important result was that a considerable proportion of children were able to estimate the risk associated with most items of the present study, and the linear association between children’s ratings and adult’s ratings was very high. This finding supports the view that the learning of the risk associated with various technologies, common in society, is a fast process, depending probably much more on exposure media information and family discussion (socialization) than on exposure to everyday reality.