The first International Conference on Earth Observations and Societal Impacts, ICEO&SI 2011, was hosted by Taiwan Group on Earth Observations and National Taiwan Ocean University in Keelung, Taiwan. It attracted more than 160 national and international participants including professors, researchers and students in universities and research institutes, engineers and technicians from governmental and private sectors and other related industries, and 34 oral papers and 22 posters are collected in the fields of ecosystems, biodiversity, disasters, GIS, energy, water, weather and climate.