This is a detailed record of the proceedings The Ninth International Symposium on Gaseous Dielectrics held at the Turf Valley Resort and Conference Center, Ellicott City, Maryland, USA, May 21-25, 2001. It covers advances and developments in a wide range of basic, applied, and industrial areas of gaseous dielectrics. The volume deals with fundamental contributions to the basic physics of gaseous dielectric materials and the understanding of basic gas discharge mechanisms and plasmas. It also deals with advances in gas-insulated equipment, especially gas-insulated transmission lines, gas-insulated transformers, and gas-insulated arc and current interrupters and the associated issues of recycling and handling of gas dielectric gases and mixtures. Included in this volume are recent developments in basic discharge and breakdown mechanisms, modeling and simulations of electrical and plasma behavior of dielectric gases, partial discharges and diagnostics, high-pressure gas dielectrics (especially SF6/N2 gas mixtures), gas decomposition, effects of particle contamination on the gas dielectric properties, and recycling of used SF6.