This Festschrift volume contains the proceedings of the conference Mathematical Methods in Computer Science, MMICS 2008, which was held during December 17-19, 2008, in Karlsruhe, Germany, in memory of Thomas Beth. The themes of the conference reflected the many interests of Thomas Beth. Although, these interests might seem diverse, mathematical methods and especially algebra as a language constituted the common denominator of all of his scientific achievements. The 12 contributed talks presented were carefully selected from 30 submissions and cover the topics cryptography, designs, quantum computing, algorithms, and coding theory. Furthermore, this volume contains two invited talks held at the conference. One focuses on the area of coding theory and symbolic computation, an area especially appreciated by Thomas Beth, because it combines algebra and algorithmics. The other one discusses quantum information, which again was a focus of Thomas Betha (TM)s research.