This book constitutes the refereed proceedings of the 21st International Conference on Automated Deduction, CADE-21, held in Bremen, Germany, in July 2007.

The 28 revised full papers and 6 system descriptions presented were carefully reviewed and selected from 64 submissions. All current aspects of automated deduction are addressed, ranging from theoretical and methodological issues to presentation and evaluation of theorem provers and logical reasoning systems. The papers are organized in topical sections on higher-order logic, description logic, intuitionistic logic, satisfiability modulo theories, induction, rewriting, and polymorphism, first-order logic, model checking and verification, termination, as well as tableaux and first-order systems.