Cost of Software Quality (CoSQ) is a pressing concern for most project managers. It is estimated that around 40% of the software budget is spent unwisely on quality improvement and testing activities. In industry, the investment in quality improvement activities is distributed evenly on the software artifacts without taken into consideration the risk and significance issues associated with them. This book presents a quality economic model for software development projects. The model optimizes the investment assigned to quality assurance activities by analyzing the relationship between the time and cost spent on a quality assurance technique and the gain in software quality. This book is useful for project managers and quality assurance practitioners who want to make informative decisions on their quality assurance plans. It is also helpful to students and researchers to understand the trade-off mechanism between cost, time and quality constraints during software development process.