Delays on construction projects constitute a major source of concern due to its associated cost increases and loss of revenue. The Gulf Cooperation Council (GCC), of which Oman is a member, faces huge delays on their projects. Such delays in the GCC were among factors fingered in the collapse of the UK's Carillion. Despite cultural similarities, substantial variability exists within the GCC construction sector which requires country-specific studies. The quest to understand delay causes results from the need to curtail wastes and adjust to the new regime of low commodity prices. There is a dearth of studies specific to the governorate of Muscat exploring the causes of delays and this study seeks to fill that gap. A structured survey questionnaire was administered at two independent events organized by the RICS and ICE in Muscat. The top causes of delays ranked using the Relative Importance Index (RII) include variation and changes in design, Poor site management and supervision, ineffective planning and scheduling, unclear and inadequate details in drawing, poor qualification of the contractors and technical staff, delay in material delivery, and shortage of labor. Contractors were found to be most likely to cause delays among the 6 categories of sources.