The use of earth as a constructive material has had a widediffusion in the world since very old times. Nevertheless, in spiteof the ecological and cultural qualities of the earthen architecture,contemporary society rejects it because they consider it obsoleteor insecure. This perception has as one of its origins the loss of thetraditional constructive knowledge that sustained it and the lack ofmodern studies that can replace it. The information referring to theconstructive technologies usually is dispersed in specialized publicationsthat are not widely spread. In order to manage to revalue thepatrimonial earthen construction and to generate new buildings, itis necessary to understand its qualities and limitations. The presentarticle exposes a series of data about the earth characterization,designing criteria and constructive processes of the three mostknown systems: adobe, rammed earth and bahareque.