In the Netherlands, the built environment is responsible for half of all raw material consumption and contributes 40% of the total country’s waste production. This characterizes the current prevalent unsustainable take-make-dispose process. To address the significant impact, a transition to a circular economy that prioritizes materials and circulates resources is essential, operationalized through the application of circular strategies. Adaptive reuse projects oUer significant potential to support this transition by extending the lifespan of existing buildings. However, existing literature highlights several barriers that hinder the eUective integration of circular strategies in adaptive reuse projects. This includes fragmented collaboration and the absence of structured guidance on organizing the development process. While strong collaboration across the development process is recognized as a key enabler, there is little insight into how it should be organized. This lack of guidance is especially critical in the early development phases, where key decisions are made that shape the project’s potential for circular outcomes. Moreover, the developer’s important role in facilitating collaboration is often approached from a general perspective, without a specific focus on their viewpoint or position. To address this, this research aims to answer the following research question: ‘How can Dutch real estate developers organise the early phases of the development process to support the integration of circular strategies in adaptive reuse projects?’ To arrive at an answer, this research combines theoretical research with qualitative empirical research. A multiple case study is conducted, drawing on interviews and document analysis to provide in-depth insights. A focus group with real estate developers was undertaken to validate cross-case findings and to explore explanations for results not fully captured by theory or cases. The study identifies the distinct role of each early development phase, inception, feasibility, and design, in supporting circular outcomes. It also outlines key circular strategies, actor roles, and phase-specific activities that enable integration of circular strategies in adaptive reuse projects. The findings emphasize that the early development phases do not follow a strictly sequential order. Instead, feasibility and design often progress iteratively, shaped by project-specific conditions and evolving circular ambitions. Furthermore, the study reveals that a developer can play a proactive role by aligning actors with circular ambitions. These insights are synthesized into a normative framework, providing phase-specific guidance for real estate developers in organising the early phases of adaptive reuse projects to support the integration of circular strategies.