Abstract : This work analyses the origin of conservation ethics' knowledge among the employees of three national libraries (New Zealand, Wellington; France, Strasbourg; Switzerland, Berne). For each of these countries, one notices that the liveliest conservation ethics' notions are related to contexts specific to each country. Assuming that knowledge based on an empirical or collective experience is firmly anchored in each individual, one can deduct that a conservation ethics' education using this type of experience has more chances to come to fruition. In this present case, this would enable the libraries to better respond to the legal engagements they are tied to. These legal mandates ask them to preserve and conserve their collections for the posterity. An online survey allowed collecting information by the employees of those three institutions. Specific context could be localised for those countries. Using those specificities, it is suggested to adapt the conservation ethics' education at professional level, to lead staff to take responsibility towards conservation issues as soon as they start to work for the institution and to maintain this knowledge up to date.