There are not many interdisciplinary scientific fields as formal language theory. In this volume, it is presented as the very intersection point between mathematics, computer science, linguistics and biology. This work is a collection of papers on classical topics in computer science-inspired formal languages, as well as other ones showing new concepts and problems motivated in linguistics and biology. The papers are organized in four sections: Grammars and Grammar Systems; Automata; Languages and Combinatorics; and Models of Molecular Computing. They clearly prove the power, wealth and vitality of the theory nowadays and sketch some trends for its future development. The volume is intended for an audience of computer scientists, computational linguists, theoretical biologists and any other people interested in dealing with the problems and challenges of interdisciplinarity.