This book arose from the Euroconference "Algebraic Combinatorics and Applications" held in Gössweinstein, Germany, in September 1999, where both senior and young researchers in pure mathematics, applied mathematics, computer science, physics, and chemistry from different European countries met. The main theme of the conference was group actions in various areas, a wide spectrum of which is presented in these proceedings. This volume will be a useful tool for researchers and graduate students in discrete mathematics and theoretical computer science.