The Passive Solar Components and Systems Testing (PASSYS) program was described in detail, from its goals to its accomplishments. That European project had seven participating countries, Belgium, Denmark, France, Germany, Italy, the Netherlands and the United Kingdom. Test sites for the programs were detailed also. During PASSYS II, (a second phase of PASSYS,) model validation and improvements were developed through the COMPASS and PASLINK projects. The integrated approach of PASSYS, and structure of PASSYS cell testing were outlined. Combinations of advanced measurement techniques, statistical analysis, and standardized procedures were developed through PASSYS. This first attempt at bringing research results into practice illustrated that such an approach can be successfully used to evaluate the potential for innovative Glazings. 9 figs.