A fellow of both the American Academy of Arts and Sciences and the American Geophysical Union (AGU) as well as a member of the National Academy of Sciences, Tony Dahlen is widely considered to be the most outstanding theoretical seismologist in the world today. Dahlen received his PhD from UC San Diego in 1969 and joined Princeton University's department of geological and geophysical sciences the following year as an assistant professor. Promoted to associate professor in 1975, he was appointed professor of geophysics in 1979 and chair of the department of geosciences in 2001. He served twice as a visiting professor at the Institut de Physique du Globe de Paris, in 1977–78 and 1993–94. The recipient of Sloan and Guggenheim fellowships (1971–73 and 1993, respectively), the 1986 Best Paper Award from the Structural Geology and Tectonics Division of the Geological Society of America, the AGU 2002 Fall Meeting's Gutenberg Lectureship, and the AGU's 2003 Inge Lehmann Medal, Dahlen has served on numerous panels and committees and as associate editor of the Geophysical Journal of the Royal Astronomical Society. Besides the AGU, his professional-society memberships include the Seismological Society of America, the Royal Astronomical Society, and the Society for Industrial and Applied Mathematics. His research interests include theoretical global seismology, free oscillations of aspherical, anelastic, and anisotropic Earth models, seismic wave propagation in heterogeneous media, mode-ray duality, mechanics of earthquake sources, Earth's rotation, and the mechanics and thermodynamics of brittle friction mountain building.