Until the end of 1990 we mainly had single media surveys in Denmark to be used in the media-planning process. Thus, because of the widely different methods, it was often difficult for both media owners and users (advertisers, planners and buyers) and researchers to make optimum use of these tools. On the basis of the conclusions from a 'future workshop' (moderated by a psychologist), with both advertisers and media planners as participants, it was thus decided to develop the Danish Multi Media Index on the basis of the National Readership Survey . In the past year, the Danish Multi Media Index has developed tremendously, from being primarily an index of print media to becoming a Multi Media Survey with information on television, radio, print media, cinema and outdoor. The Index is now not only a media-planning tool but also a Marketing Information System capable of meeting the needs of all parties in the media business. The objective was to provide a tool for all stages of the communication planning process, providing documented answers to the questions of advertisers and planners. One of the greatest innovations is in the field of TV planning, in which a quarterly, four-week diary is used which also includes usage of other media. This diary is the only tool in Denmark which provides data for media group optimalisation and analyses of real accumulation over time for comparison between media groups. On the basis of the data from this panel survey, AIM Research A/S has developed a long asked-for op- timalisation model. As the Danish Multi Media Index is a single source system, and on account of a fusion of two databases (the TGI and a brand-tracking index), each consisting of 12 inter- views, it is 'only' necessary to conduct a total of 37 interviews. If all the indexes making up the Multi Media Index were instead separate indexes, a total of approx. 170 interviews would have been necessary. In addition to the quality of the data in the Multi Media Index, this naturally results in considerable financial savings, both for the owners and for the users.