In the early morning of 21 September 1999, a devastating earthquake struck the central region of Taiwan. This earthquake became known as the Chi-Chi Taiwan earthquake. Immediately after the occurrence of the earthquake, the National Center for Research on Earthquake Engineering (NCREE) organized reconnaissance teams to investigate the damage in the earthquake-affected area. The purpose of this paper is to describe the inter-collaborations and actions that were taken by NCREE and the engineering research community. This paper also describes the damage situation from an engineering point of view that includes fault investigations, studies of strong ground motion characteristics, building and bridge damage investigations, geotechnical damage surveys, and lifeline damage investigations. The NCREE's emergency response decision support system and the HAZ-Taiwan earthquake loss assessment program are also described.