Circular Economy is receiving worldwide increased attention as a way to decouple economic growth from the consumption of finite resources. Cities and urban regions are a growing source of resource consumption and are increasingly recognized by national and regional governments as an arena to mitigate resource problems associated with urbanization. Coordinating this transition in this urban regions implies the need for tools that can monitor the environmental, social, and economic impacts of established targets. However, currently there is a lack of knowledge on how to design regional indicators which are scientifically sound, relevant, and easy to use in practice. This thesis presents method for the rigorous validation process of region specific criteria which guarantees the indicators are scientific, relevant, and useful. The method comprises a validation of criteria in three stages: desk research (self-validation); expert interviews (scientific validation); focus group (social validation). The results from the case study in the Metropole Region of Amsterdam suggest that the purpose of using indicators is to among others encourage economic activity, attract talent companies and investors, enable benchmarking, and support political action. The indicators should measure one of the following drivers, i.e. knowledge dissemination, circular procurement, resource utilization, and cluster development. Furthermore, the indicators should be based on the CE principles, i.e. modular design, zero waste, closing loops, new business models. A credible indicator, provides early warnings transparency in method. Robustness of the indicator is guaranteed by an international standardized method, statistically validated data, and sensitive data. Furthermore, the indicator should be easy to understand and data should be collected at reasonable time and costs. Some strengths of applying the 3S methodology prove to be that a detailed self-validation phase can help to become more familiar with the regional CE strategies, which facilitates interpretation during the scientific- and social validation phases. Furthermore, incorporation of independent experts' judgements through the use of in depth interviews can help to bring scientific credibility to the indicator selection process. The results from the desk research and the interviews show that the various stakeholders engaged in the process hold different preferences and values regarding the purpose of indicators and the aspects that should be measured in the region. The focus group shows that consensus can be built among stakeholders regarding these opinions. Concluding, this method offers an opportunity for planners, policymakers, and researchers to identify key criteria for a regional CE indicator framework; thus providing a first step to develop a scientific, relevant, and useful set of CE indicators for a region.