George Papanicolaou, the Robert Grimmett Professor in Mathematics at Stanford University, is one of the world’s leading applied mathematicians. He has been one of the pioneers in the study of diffusion in inhomogeneous or random media and in the mathematical analysis of multi-scale phenomena. He is a Fellow of the American Academy of Arts and Sciences, a member of the U.S. National Academy of Sciences, a past invited and plenary speaker at the International Congresses of Mathematicians, and a recipient, in 2006, of the von Neumann prize from the SIAM. He served as a member of the SAC from 1996 to 2000.