This Bulletin of the New Zealand Society for Earthquake Engineering (NZSEE) is a collaboration with the New Zealand Geotechnical Society (NZGS) and the Structural Engineering Society New Zealand (SESOC), with papers on the preliminary observations of the 2010 September 4, 04:35 (NZST; September 3, 16:35 UTC) Darfield (Canterbury) earthquakes. This Introductory paper summarises preliminary observations of the earthquakes and the performance of ground, structures, non-structural elements, and lifelines; the assessments of usability; and the communication of information amongst the science and engineering communities.