The examples on which I will draw include those of Alto Mayo where 7, 000 homes were rebuilt after the 1990 earthquake and the regional reconstruction Program undertaken by the Corporation Nasakiwe in Colombia. Much human vulnerability to hazards is man-made. Since the risks relating to disasters and dwellings are largely social products, anyone intending to facilitate change must look at how and why people build as they do in any particular place. It is useful to compare the main features of traditional and modern building technologies.