This volume is a sequel to the books Fractals: Theory and Applications in Engineering (Springer-Verlag, 1999) and Fractals in Engineering. From Theory to Industrial Applications (Springer-Verlag, 1997), presenting some of the most recent advances in the ?eld. It is a fascinating exercise to follow the progress of knowledge in this interdisciplinary area, as witnessed by these three volumes. First,con?rmingprevioustrendsobservedin1997and1999,appliedma- ematical research on fractals has now reached a mature level, where beautiful theories are developed in direct contact with engineering concerns. The four papers in the Mathematical Aspects section constitute valuable additions to the set of tools needed by the engineer: Synthetic pictures modelling and rendering in computer graphics (Theory and Applications of Fractal Tops, by Michael Barnsley), curve approximation and fractal B-splines (Splines, Fractal Functions, and Besov and Triebel-Lizorkin Spaces, by Peter Mas- pust), deep understanding of the Hol .. derian properties of certain stochastic processes useful in a large number of applications (H.. olderian random fu- tions, by Antoine Ayache et al. ), and study of the invariant measure of a coupled discrete dynamical system (Fractal Stationary Density in Coupled Maps,byJu..rgen Jost et al. ). The second section of the book describes novel physical applications as well as recent progress on more classical ones. The paper A Network of Fr- tal Force Chains and Their E?ect in Granular Materials under Compression by Luis E. Vallejo et al.