“Dialogue” is the trendy word of the moment. The word “dialogue” can be found in the call to access European funding, in the works of Science Communication scholars, in presentations of science education projects, in the mission of new science centres. “Dialogue” is also a word reported by mass media regarding politicians' and scientists' speeches on general issues as well as on local or specific problems such as environment, health, energy, etc... This new magic word is frequently repeated and opens many doors (or perhaps it simply helps to make a good impression). However, there is the risk of ignoring the real meaning and functioning of the word. JCOM is therefore asking a number of experts involved in “dialogue” the following questions: what does it really mean? What are the theoretical principles, the practical opportunities, but also the risks and limits of “dialogue”?