Many companies are flocking to obtain ISO 9000 certification in the hope that it will provide them with new market opportunities, as well as improved product quality and business performance. At the same time, other companies believe that the standards do little to improve product quality and business performance—they only provide good housekeeping. The purpose of this study is to determine the impact of ISO 9000 on the business performance of America's best performing manufacturing companies by utilizing a large database. Furthermore, we will investigate if ISO 9000 certified companies included in the above database are more likely to have in place a wider variety of quality management tools.