Earthen buildings are highly vulnerable to the destructive action of earthquakes, as is tragically revealed by the considerable damage and loss of life that takes place during earthquakes occurring in areas where construction with earth is prevalent. Although many historical earthen monuments have survived strong earthquakes, contemporary vernacular dwellings built with earth have shown extremely poor response in recent earthquakes. Many persons, most of them very poor, have lost their lives due to the collapse of their weak and fragile houses. It is urgent, therefore, to find simple technical solutions to improve the seismic performance of earthen buildings. This paper first describes the seismic response of traditional, unreinforced earthen buildings. It then presents some of the reinforcement techniques developed over more than 35 years of research carried out by the Catholic University of Peru. Finally, it briefly outlines the challenges involved in the dissemination of economical and safe construction techniques, in order to mitigate the risk of earthen buildings in seismic areas. © Springer-Verlag Berlin Heidelberg 2011.