The London Transport Executive is a very important media owner. Gallup, who had previously worked with the LTE on commercial evaluation of posters, was asked if it could assess the extent to which posters shocked or offended the public. A form of hall test was developed, in which adults were invited to express their views of a set of posters chosen to be near the borderline. This indicated guidelines by which posters could be assessed. The experiment was repeated at a London comprehensive school using some posters already tested with adults and some new ones to get the reactions of school children. The findings were somewhat different from those expected. Children were far more sensitive than adults thought in some areas, and less in others. The paper illustrates the findings in the four areas surveyed, namely: Pregnancy and abortion, underwear, sex/comedy films, and violent films.