This Volume presents the proceedings of the 1995 Advanced Study Institute entitled "Fundamentals and Applications of Gas Phase Ion Chemistry" held at Grainau, tlt Germany during the period 7 _IStlt August, 1995. The Institute brought together over SO scientists from many countries and, for the first time in this series, we were delighted to be able to welcome representatives from a number of countries in Eastern Europe. This was the sixth in a series of NATO-sponsored Institutes devoted to various aspects of the physics and chemistry of gas phase ions. Although there continued to be a strong emphasis on various fundamental aspects of the subject, there was a broadening of the topics covered compared with previous Institutes with several sessions being devoted to discussing various types of application. This reflects the great expansion of the use of mass spectrometry in the investigation of biochemical and biological problems and in its use in different branches of the chemical industry such as in the investigation of polymers and other materials.