This monograph contains expanded versions of the invited papers presented at the International Symposium on the Life Cycles of Extratropical Cyclones, held in Bergen, Norway, 27 June–1 July 1994. The symposium coincided with the 75th anniversary of the introduction of Jack Bjerknes’s frontal-cyclone model presented in his seminal article “On the Structure of Moving Cyclones.” The first nine chapters present a historical overview of extratropical cyclone research and forecasting from the early eighteenth century into the mid-twentieth century. The succeeding chapters review and present contemporary research on the theory, observations, analysis, diagnosis, and prediction of extratropical cyclones. The sequence of presentations transcends the planetary scale to mesoscale scales of motion. This monograph should be of interest to historians of meteorology, researchers and forecasters. It contains material appropriate for teaching courses in advanced undergraduate and graduate meteorology. The chapter bibliographies provide a valuable source for key references on many aspects of extratropical cyclones.