The ISES Solar World Congress, held in Denver, Colorado in August 1991 attracted over 1000 participants from nearly 70 countries, making it the largest solar energy event of its kind in the world. As a lasting record of that congress, 630 papers are published here in 4 volumes of proceedings. Volume 1 is dedicated to solar energy, biofuels and renewable resources. Volume 2 contains papers on active solar and solar heat. Passive solar, socio-economic and educational aspects are considered in Volume 3, and finally the plenary sessions, and the Farrington Daniels lecture are published in Volume 4. 1991 Solar World Congress presents the very latest advances in the utilization of alternative energy resources and technology.