The circular economy is an economic model in which resources are circulated in a closed loop by adopting the R-strategies (e.g. reuse, recycling, and reduce) to minimize waste and pollution. Repurposing vacant buildings, known as adaptive reuse, is in line with the principle of circular economy, as it contributes to the reuse of the built assets instead of their demolition. In addition, this can help to conserve resources and reduce the environmental impact of building construction. Furthermore, adaptive reuse is not only necessary for vacant properties but also for obsolete buildings. Thus, it is an unavoidable practice in the built environment. This implies that adaptability should be incorporated into this kind of projects besides circularity. However, recent research revealed that many of the Dutch adaptive reuse projects were implemented without adequate consideration of circular solutions. Accordingly, this research project aims to develop practical guidelines that could guide practitioners on operationalizing circularity and adaptability in the adaptive reuse of vacant and obsolete real estate. Sequentially, three approaches with different research methods were followed to answer the main research question: ‘’How can circularity and adaptability be promoted in the reuse of vacant and obsolete real estate?’’ The first approach is the documentation of existing knowledge. This approach was followed to answer the first sub-question: ‘’What are the criteria and measures for reusing obsolete and vacant buildings in a circular and adaptable manner?’’ In this approach, a literature review was carried out. The literature review led to the identification of 12 criteria and 8 measures for circular and adaptable adaptive reuse. The second approach is case studies on circular adaptive reuse projects of vacant and obsolete buildings. This approach was followed to answer the second sub-question: ‘’To what extent are circularity- and adaptability-related measures implemented in reusing vacant and obsolete buildings?’’ In this approach, three research methods were used in two case studies, namely: archival research, interviews, and field observation were used simultaneously. The findings of the cross-case analysis of two case studies resulted in adding 8 measures to the previously defined measures from the literature, totaling 16 measures. The third approach is the formulation and validation of guidelines based on knowledge gained from theory and practice. This approach was followed to answer the third sub-question: ‘’How can guidelines guide professionals on how to promote circularity and adaptability-related measures in the reuse of vacant and obsolete buildings?’.’ In this approach, the guidelines were synthesized based on knowledge gained from the literature and findings of the two case studies. The results of developing and validating the guidelines contributed to adopting 13 guidelines. Overall, the validation outcomes indicate that the guidelines are informative and useful when visualized. However, they need to be updated constantly for their applicability in practice.