Evaluative research clearly shows that public health campaigns can be effective. However, it is important that theories and results of communication research are applied in the planning phase of a health campaign. Questions to be considered are: What are the specific goals of the campaign? Who is the target group, and who selects it? What is the message to be conveyed, and who shall develop it? What is known about the effectiveness of the media in reaching the target audience? And last but not least: Only evaluative research can prove if a campaign has reached its goals!