Phrasing the question is one of the most delicate points of a referendum. A first problem is to choose the most important alternatives. Several procedures to select these alternatives and to avoid some kinds of manipulation, exist. There are a lot of arguments for the voting on principles, but also a lot against. The Swiss criterion for «unity of matter» (to avoid two items in one question) is not workable; a new criterion is proposed. The danger of suggestivity (caused by loaded words, by arguments in the question, or by a failure of communication) is real. Rules to prevent these dangers are discussed. Finally, some remarks are made on the problem «who decides on the question?». A neutral commission is wishful.