ABSTRACT Various reports have suggested that agile practices empirically improve the quality of software, as a result, reduce the amount of rework in software projects. On the other hand, agile practices incur time or personnel overhead, making it subject to managerial cost concerns. This study investigates the cost effectiveness of three popular agile practices: Test-Driven Development, pair programming and pair testing, using a developed system dynamics tool called the Predictive Continuous Delivery Model (PCDM). The Return-on-Investment (ROI) for TDD, pair programming and pair testing were 0.34, -0.60 and -0.64 respectively. Hence, from an economic perspective, only TDD is worth adopting in continuous delivery projects.