Consensus, defined as the position on which most scientists specialized in a given field agree at a given time, is a key aspect in increasing the readability, credibility and, ultimately, the use of scientific knowledge in public (evidence-based health policy). This article presents several methods aiming at developing scientific consensus between experts, such as the conventional or rapid Delphi approach, the nominal group technique, the RAND-UCLA appropriateness method and the consensus development conference. These methods are used to synthesize expert judgements when uncertainties persist in the literature - each with its own specificities in terms of duration, number of steps and expert participants enlisted, as well as the ways in which they are involved.