A critical issue that faces the Saudi Arabia Oil and Gas Sector (OGS)âs projects is the high level of uncertainty in the successful delivery of those projects. That high level of uncertainty makes it vital to monitor and control project performance for limiting financial losses, avoiding cost overruns, and improving predictability. One of the fundamental tools that sets the framework for project performance is the project Scope of Work (SOW). Having an effective project SOW at the front end the project is challenging for project practitioners and is an issue that needs to be addressed; as its development process and output can significantly affect the later stages of the project life cycle. The aim of this study was to develop a clearer understanding of the project SOW role in a project development and to make practical recommendations for its improvement by investigating project team membersâ perceptions of the SOW development process in two Saudi Arabian Oil and Gas companies. This research adopts a qualitative approach, a case study strategy and focus group discussions to collect primary data. The results suggested that the project SOW development process is the foundation for another twelve key project management processes that need to be considered in order to successfully complete a project On Scope, On Time, On Cost and On Strategy. To be considered effective, the project SOW should have the following four characteristics of: formality, usefulness, effective content elements and effective language quality. In addition, the project SOW should support effective decision making, risk management, project planning and project monitoring and control. The results show that the project SOW in Saudi Arabia OGS is developed in several phases as part of Front-End Loading (FEL) development and final project SOW is developed and approved at the end of the 2nd phase of FEL (FEL-2). It was found that there are eleven key enablers, such as clear vision, targets, and objectives; effective stakeholdersâ engagement; and effective assurance review process, for producing an effective project SOW. While eleven key barriers for producing an effective SOW were identified such as: absence of reward system; insufficient training programs; and insufficient budget. Therefore, enhancing the key enablers and overcoming the barriers may facilitated improvements in the project SOW development process. This study recommends that companies need to pay closer attention to the design of the temporary organisation and accordingly set their strategy, structure, process, rewards and people. The researcher details some implications, acknowledges some limitations and provides recommendations for future research in this area.