A description is given of the defect prevention process. It consists of causal analysis meetings to identify the root causes of errors and suggest preventive actions, an action team that implements the preventive actions, stage kickoff meetings to provide feedback to developers at each stage of the development cycle, and data collection and tracking of associated data. Typical preventive actions include process changes (including common error lists, checklists, and other forms of feedback), new or improved tools, improved education, product changes, and improved communications among developers. The defect prevention process has been applied successfully in a number of software development organizations within IBM, with significant reduction in errors. The application of this process to different types of organizations involved in software development, including design, development, test, information development, planning and requirements, and human factors is described. For each type of organization, different processes, tools, and methodologies are used. It is shown that the defect prevention process can be applied to errors arising from each particular process.>