The Thomas Stieltjes Institute for Mathematics is a Dutch research institute in mathematics, in which participate the University of Amsterdam, the Free University of Amsterdam, the Delft University of Technology, the Eindhoven University of Technology, the University of Leiden and the Erasmus University of Rotterdam. The Institute collaborates with the Centre for Mathematics and Computer Sciences (CWI) in Amsterdam and with the European Institute for the Study of Randomness (EURANDOM) in Eindhoven. The University of Leiden is administrator of the Institute.The Stieltjes Institute, founded in 1992, carries out research in four main areas of fundamental and applied mathematics: Algebra & Geometry, Analysis, Stochastics, and Operations Research. It has been accredited as a Research School by the Royal Netherlands Academy of Arts and Sciences (KNAW). Each year an outstanding mathematician joins the Institute as a Stieltjes Visiting Professor. The Institute has a research training programme for Ph.D. students and each year a Stieltjes Prize is awarded for the best Ph.D. thesis in the Institute. Mathematics has many different branches and two different aspects: the fundamental and the applied. However, it is a single coherent body of knowledge. This is demonstrated time and again by sometimes unexpected links between the various parts of mathematics and by the possibilities to apply even the most abstract developments. Also, direct contact with fields of application often generate new challenges for mathematical research. For this reason the Stieltjes Institute does not stress the distinction between fundamental and applied mathematics, and encourages research that crosses the dividing lines between the various parts of mathematics. The Stieltjes Institute combines the expertise of three general, two technical and one economics and medical university. This provides an excellent opportunity for interaction between mathematics and its applications in the life sciences, the natural sciences and engineering, computer science and economics.