This text is the result of the 1995 Second Symposium on Human Interaction with Complex Systems. This symposium brought together a number of experts in the area of Human-System Interaction to provide answers to a variety of problems in four major areas of HSI, cognitive ergonomics of complex systems, information display and decision aiding, progress in human-system interaction, and human modeling and simulation. In 1994, a series of symposiums on human interaction with complex systems were initiated. It was then that various ideas surrounding HSI for today and tomorrow were discussed by many scientists in the related disciplines. As a follow-up, in 1995 the Second Symposium was organized. The objective of this symposium was to attempt to define a framework, principles, and theories for HSI research. This book is the result of that symposium.