Despite the economic importance of nematodes for sheep enterprises, it is often difficult to convince producers to adopt best practice in worm control. In this paper we discuss key issues in effecting change by communicating worm control messages. The adoption of new strategies is affected by many factors including the relative advantage, complexity, compatibility and the ability to trial the proposed change. The visibility of the problem to be solved and proposed positive outcome are also important. Extension campaigns from the last 30 years, including " WormKill" and " CRACK" , are used as examples, and future opportunities and tools, including the internet, for promoting best practice in sheep worm management are discussed.