This dissertation studies the integration of Virtual Reality (VR) into the early stages of the architectural design process, particularly during massing studies. The research proposes a framework identifying the necessary knowledge domains and technologies to facilitate this integration. Traditional design tools often restrict architects' ability to fully explore spatial qualities and contextualize their ideas within the project site, limiting their understanding of spatial relationships, scale, and proportions. By merging VR technologies into the early design stages, architects can better visualize their proposals within the site context, iterate more rapidly among massing design alternatives, and enhance decision-making. The research, based on a literature review, class observations, user studies, immersive case studies, and the Delphi method, examines how VR can support the exploration of design alternatives at a 1:1 scale, enabling real-time feedback and iterative processes. The findings highlight the opportunities and challenges within the design workflow, demonstrating that VR can significantly improve design feedback, expand the thinking space and user engagement, and enrich spatial understanding. The proposed framework identifies key decision nodes and knowledge domains essential for effective VR integration in architectural practice. Additionally, the study suggests a suitable interface for VR-integrated tools and proposes a communication model between architects and VR developers. / Doctor of Philosophy / The design process consists of different stages, and the decisions made during the early phases, including massing—the study of a project's shape, form, size, and envelope configuration within its site—can significantly impact the project's overall performance and cost throughout its life cycle. As the project evolves, making changes becomes more time-consuming and expensive. This dissertation focuses on how architects can use Virtual Reality (VR) to enhance massing studies in the early design stages. For each architectural project, architects need to examine how it will fit into its location, its impact on the context, and how it will interact with site features such as sunlight, land shape, directionality, adjacent buildings, and greenery. Traditionally, tools like computer software, 3D models, sketches, and prototyping help visualize these elements, but they can sometimes be limiting, making changes difficult once a plan is set. This research investigates how integrating VR into early design decisions allows architects to "step into" their designs, better explore alternatives, and improve decision-making. By using VR, architects can more effectively visualize their designs within the actual site context, quickly test different massing options, and refine their decision-making process. Based on a literature review, classroom observations, user studies, and immersive case studies, the research proposes a framework that identifies key knowledge areas, technologies, and themes essential for integrating VR with the design process and understanding spatial relationships.