A literature review on the subject of ambient vibration testing is presented, along with a review of a recent study to illustrate sta~f-the-art in the application of the ambient vibmtion method. Reports 00 testing of full-scale structures by the ambient vibration method began to appear regularly around 1970, with about 3/4 of all contributions devoted to the experiments in buildings, dams, chimneys and silos, and about 114 to bridges. Since 1985, there are only about 3 papers per year, world-wide, dealing with this subject. The reviewed study is of a seven-story reinforced concrete building in Van Nuys, California, damaged by the 17 January 1994 Northridge earthquake and its early aftershocks. Two detailed ambient vibmtioo surveys were conducted soon after the earthquake. The apparent frequencies and two- and threedimensional mode shapes for longitudinal, tmnsverse and vertical vibrations are presented in this paper. The attempts to detect the highly localized damage by simple spectml analyses of the ambient noise data were not successful. It is suggested that very high spatial resolution of recording is required to identify localized column and beam damages. The loss ofaxia! capacity of the damaged columns could be seen in the vertical response of the columns, but similar modemte or weak damage typically would not be noticed in ambient vibration surveys.