World renowned economic theorist Kenneth J. Arrow, Nobel Laureate in Economics (1972) and professor emeritus at Stanford University (USA), has been appointed to the ICTP Scientific Council. He is the first member of the Council to be trained in economics and the social sciences. Arrow has used a variety of mathematical tools and models to examine the economics of information and organization, collective decision-making and theories of justice, and ecological economics. The Nobel Prize, which he shared with Sir John Hicks, All Souls College, Oxford University, UK, was awarded for "pioneering contributions to general economic equilibrium theory and welfare theory." Arrow's diverse areas of expertise and unique applications of mathematics should prove particularly helpful to ICTP's new research fields, especially the recently launched ecological economics programme. Arrow will attend the next ICTP Scientific Council Meeting, scheduled to take place 17 May.