Sigurdur Helgason has been Professor of Mathematics since 1965. He graduated from the University of Iceland in 1946, and received the Ph.D. from Princeton in 1954 under the direction of Salomon Bochner. He then came to MIT as a CLE Moore instructor. Subsequently he was appointed lecturer at Princeton, 1956-57, and Louis Block Assistant Professor at the University of Chicago, 1957-59. Following a year at Columbia, Professor Helgason joined the MIT mathematics faculty in 1960. His research involves new integral geometry methods on symmetric spaces, resulting in fundamental existence theorems for differential equations on symmetric spaces and results on the representations of their isometry groups. He has also introduced a Fourier transform on symmetric spaces and proved the basic results for this transform. A prior Guggenheim fellow, Professor Helgason received the Institute's first graduate student teaching award in 1975. He served as graduate chairman for seven years. He was given the Børge Jessen Diploma Award by the Danish Math. Society (l982), and the Major Knights Cross of the Icelandic Falcon (1991). In 1988, Professor Helgason received the AMS Leroy P. Steele Prize for Seminal Contributions, "for his books Differential Geometry, Lie Groups and Symmetric Spaces, and Groups and Geometric Analysis." These were followed by the 2008 book "Geometric Analysis on Symmetric Spaces". He was given the Doctor Honoris Causa from the University of Iceland (l986), the University of Copenhagen (1988), and the University of Uppsala (1996). Professor Helgason is a Member of the Icelandic Academy of Sciences (l960), Fellow of the American Academy of Arts and Sciences (l970), and Member of the Royal Danish Academy of Sciences and Letters (l972).