Sustainable development lies at the heart of Oman Vision 2040(Oman vision 2040, 2019). Although the economic; and human aspects of sustainable developments are the main focus of the future direction of the country, the role of the built environment as a key component of the Omani sustainable development agenda has been recently acknowledged by the government. However, the development in this area is rather slow when compared to other Gulf Cooperation Council (GCC) countries who have already introduced sustainability rating systems for buildings such as Pearl Rating System Tool in Abu Dhabi and Qatar Sustainability Assessment System. Most of these systems were developed based on international sustainability rating systems i.e. LEED and hence, adopted a top-down approach where the inspiration and cultural values of the wider community might have been insufficiently considered. In spite of the tendency towards a sustainable built environment in Oman, there has been a lack of clear understanding of sustainability in a way that reflects Omani people's aspirations, values, preferences and priorities. Equally important, earlier endeavours in this field did not investigate sustainability components in the built environment as perceived by stakeholders, including end-users and decision makers, in Oman. This forms a major obstacle in the way of developing a local building sustainability rating system. Therefore, the aim of this study is to elicit the Omani stakeholder's perception of a sustainable built environment and identify sustainability components as perceived by the Omani stakeholders. In addition, the study explores the existence of differences among stakeholder groups in sustainability knowledge based on socio-demographic factors such as gender, age, education level, influence level, background and previous experience in sustainable projects. The study adopted the social constructionism theory as an overarching approach and hence, employed identification and mapping, elicitation, and consensus development methods in a three-step data collection process. The first step involved stakeholder identification and mapping using the power-vs-interest matrix technique. This technique allowed the researcher to identify and classify stakeholder groups into four categories namely, crowd, subjects, context setters and players. This was followed by an exhaustive freelisting exercise with a sample of 116 stakeholders who covered the four categories outlined in the previous step. An effort was made to balance the sample across stakeholder's categories and socio-demographic factors. The cut-off in sample size was based on the notion of saturation point upon which no new terms are added by any further addition to the sample size. After the freelisting data is filtered for inconsistency and repetition following the method's protocol, the data was used to calculate the Salience Index for each elicited unique term. The last step in the data collection process involved a Pile sorting workshop during which representatives of stakeholder groups worked collaboratively to develop consensus in order to categorize the terms that were elicited in the previous stage. The data were analysed statistically and inferentially using Statistical Package for Social Sciences (SPSS). The results showed that the most salient terms for Omanis are Green Area followed by Natural Ventilation and Using Solar Energy. It was also found that out of the 234 unique terms elicited, there are 27 terms that formed the core components of sustainability in the built environment as perceived by Omanis i.e. most salient terms. These terms are consensually categorized into four categories by the stakeholder representatives during an interactive pile sorting workshop. These categories were given titles based on the terms classified under each category by the stakeholder representatives themselves: Materials and Construction, Social Requirements, Efficient Design, and Cost Optimization. Therefore, it was concluded that the four groups and the 27 terms represent potential structure -i.e. categories and their indicators- for the development of an Oman-specific sustainability rating system. Moreover, the inferential statistical analysis carried out (Mann-Whitney U test and the Kruskale Wallis test) showed that some of the socio-demographic factors are associated with differences in sustainability knowledge. In particular, gender, education and stakeholder groups were found to have a significant effect on sustainability knowledge among stakeholders. However, the analyses showed that there were no significant differences in sustainability knowledge based on stakeholders influence level (crowd, subjects, context setters and players), which in turn suggests that those who have the power to change and influence do not necessarily have better knowledge about sustainability. Therefore, this thesis calls for immediate action to start a large-scale programmer to promote sustainability knowledge and practices among all built environment stakeholder groups including policymakers. Equally important, the thesis provides an evidence-based structure to develop a local building sustainability rating system based on Omani stakeholder's collective perception, values and aspirations.