Several studies investigating the causes of delay in projects in the construction industry have been conducted worldwide. This study investigates the causes of delay in construction projects in oil and gas processing facilities in Oman and serves as a case study for the Gulf Cooperation Council (GCC) countries. Using a questionnaire, data were collected from 59 project managers employed in different organizations in the oil and gas industry in Oman. The survey results showed a high degree of agreement among the perceptions of project stakeholders, clients, contractors, and consultants on the causes of project delay, and there is no evidence to suggest that the causes of project delay differ significantly according to organization size or organizational ownership. Moreover, seven factors were identified as the major causes of project delay. Although six of these identified elements are general factors that can account for delay in any project in any industry, one of thempoor interaction with vendors in the engineering and procurement stagesis found to be unique to construction projects in the oil and gas industry. The findings of this study could be of value to organizations that are planning to conduct construction projects for oil and gas processing facilities in Oman and other nations with similar environments, such as the GCC countries.