Founded in 1850, Levi Strauss is now the largest clothing manufacturer in the world. The historical development of the Company is traced, and the astonishing growth in the blue jean market from the 1950s onwards. The way that the Levi Strauss Company has organised itself to stay ahead is briefly described. Social trend information is used to provide forecasts of likely volume on a one and five year basis. Typical trends that are taken into account are discussed. The role of social trend information in the development of advertising is then discussed, with emphasis on the researcher's role as a link between the target market and the creative people. Advertising for Levi's is shown to illustrate the need for this understanding of the audience.