We often hear about software projects throwing defects during implementation and live usage. With the downturn in the Information Technology business over past two years and customers getting more knowledgeable and demanding software houses are finding it difficult to retain the bottom lines with this state of affairs. Defect Prevention discipline thus assumes immense importance in the current era. With wide adoption of the Capability Maturity Model (CMM) defect prevention still remains little understood area at various levels in the organizations. Though there has been a large amount of research literature available on the subject an introductory book on the subject was missing. The book intends to fill this gap.