It is not easy to summarize -even in a volume -the results of a scientific study con ducted by circa 30 researchers, in four different research institutions, though cooperating between them and jointly with the International Institute for Applied Systems Analysis, but working part-time, sponsored not only by IIASA's national currency funds, but also by several other research grants in Poland. The aims of this cooperative study were de fined broadly by its title Theory, Software and Testing Examples for Decision Support Systems. The focusing theme was the methodology of decision analysis and support related to the principle of reference point optimization (developed by the editors of this volume and called also variously: aspiration-led decision support, quasi-satisfying framework of rationality, DIDAS methodology etc. ). This focusing theme motivated extensive theoretical research - from basic methodological issues of decision analysis, through various results in mathematical programming (in the fields of large scale and stochastic optimization, nondifferentiable optimization, cooperative game theory) mo tivated and needed because of this theme, through methodological issues related to software development to issues resulting from testing and applications. We could not include in this volume all papers -theoretical, methodological, appiied, software manu als and documentation -written during this cooperative study.