Description:This book constitutes the refereed proceedings of the 20th International Conference on Theorem Proving in Higher Order Logics, TPHOLs 2007, held in Kaiserslautern, Germany, in September 2007. The 21 revised full papers presented together with 5 proof pearls (concise and elegant presentations of interesting examples) and the abstracts of 3 invited papers were carefully reviewed and selected from 52 submissions. Among the topics of this volume are formal semantics of specification, modelling, and programming languages, specification and verification of hardware and software, formalisation of mathematical theories, advances in theorem prover technology, as well as industrial application of theorem provers.