The general aim of mastitis control programs is to improve udder health on dairy farms. Over the last five years an intensive national mastitis program was executed in the Netherlands with the goal to improve udder health at a national level. Different groups of farmers have different motivations and should be approached differently, and their behaviour is influenced by different advisors. Therefore, as many different groups of advisors as possible should be involved in the program. Most of the veterinary practices in the Netherlands participated as did, in later years, other farm advisors. We experienced that for a successful program it is crucial to have knowledge on motivating factors of dairy farmers. Many advisors are convinced that the only way to change farmers’ behavior is through economics. We found that economics are important, but that other factors are as important in influencing farmers’ behaviour. To have a successful national mastitis program it is advisable to involve professionals on communication in designing the program. Although the technical knowledge on which the program is built should be optimal, that generally is not the bottle-neck in being successful. There often is more to gain in presenting knowledge in such a way that it is actually used, than in increasing the amount of existing knowledge.