Recent geophysical, geological and geochemical studies on the Juan de Fuca Ridge has been gathered into a special collection of manuscripts that demonstrate the interdisciplinary nature of the crustal formation and evolutionary processes. On the ridge axis, these new studies include long-term sea floor and water column measurements that indicate ''real-time'' changes due to volcanic activity and related hydrothermal flux, sea floor measurements of seismic activity detecting swarms of earthquakes near the axial zone, and submersible observations of a 2-km along-strike spacing of large-scale hydrothermal fields. Detailed sampling of axial basalts show that, in spite of abundant evidence of ''excess'' volcanic activity, the Juan de Fuca Ridge is not a traditional hot spot. On a larger scale, geophysical surveys of the ridge flanks show that the upper crust can vary in thickness by a factor of two, that crustal porosity systematically decreases with age, and the topographic forcing is the dominant control of off-axis hydrothermal circulation. Finally, the Juan de Fuca Ridge has long been a testing ground for innovative survey techniques, and this issue includes reports on the development of acoustic backscatter as a quantitative measure of basement roughness and as an indicator of the presence of lithified sediments overlying zones of fluid upwelling. ¿ American Geophysical Union 1993