Orthogonal Polynomials and Special Functions : Leuven 2002 The set of lectures from the Summer School held in Leuven in 2002 provide an up to date account of recent developments in orthogonal polynomials and special functions in particular for algorithms for computer algebra packages 3nj symbols in representation theory of Lie groups enumeration multivariable special functions and Dunkl operators asymptotics via the Riemann Hilbert method exponential asymptotics and the Stokes phenomenon. The volume aims at graduate students and post docs working in the field of orthogonal polynomials and special functions and in related fields interacting with orthogonal polynomials such as combinatorics computer algebra asymptotics representation theory harmonic analysis differential equations physics. The lectures are self contained requiring only a basic knowledge of analysis and algebra and each includes many exercises