The CCE Index developed by KAPSARC aims to measure countries’ progress in and potential for reaching circular carbon economies. It is built on the concept of the circular economy which provides a holistic, flexible, and pragmatic framework for countries to plan and implement their respective contributions toward the Paris Agreement goals. The CCE Index developed with two important distinctions: it has an exclusive focus on energy and emissions (instead of materials, products and waste), and it adds a fourth pillar to the three pillars of the circular economy: reduce, reuse, recycle, and remove. The fundamental goal of the CCE is to prevent atmospheric carbon dioxide and other greenhouse gas emissions through these four pillars, which include reducing emissions through energy efficiency and renewable energy, recycling carbon through bioenergy, reusing carbon by converting it into materials such as polymers or concrete, and removing carbon dioxide from the atmosphere through carbon capture and storage and natural sinks.  CCE index is a composite indicator comprised of a total of 47 individual variables or indicators. When aggregated together, these provide insights into how well countries are performing on these two temporal dimensions of the CCE compared to each other. The 2021 edition includes 30 countries: the 19 Group of Twenty (G20) member countries and 19 major global oil producers. The CCE Index has two sub-indices: one for measuring countries’ current performance on the various CCE activities and the other for gauging how countries are positioned to make progress toward the CCE, based on key enabling factors. The CCE Index also allows for additional comparisons among top oil-producing countries through a separate set of add-on indicators called the Oil Producers Lens, which helps estimate how these countries’ industrial performance and business environments are aligning with the CCE. Each country receives a score on a scale of 0–100 for each indicator and for the total index and its sub-indices and lenses. Separate scores are first calculated for the sub-index scores, which are then aggregated to form the total CCE Index score. In total, the CCE Index therefore consists of three aggregate scores: the CCE Performance score, the CCE Enablers score, and the total CCE Index score. Ten oil-producer-specific indicators, referred to as the Oil Producers Lens, are applied to the 19 oil-producing countries to form additional three scores: the Oil Producers Lens Performance score, the Oil Producers Lens Enablers score, and the Oil Producers Lens total score. A country’s score should be interpreted as an indication of how close it is to ideal performance, either compared to its top-ranking peers or a technical optimum. For example, a score of 66 would be equivalent to two-thirds of a potential maximum score. The CCE Index also provides a rank for each country at the index and sub-index levels to facilitate comparisons across countries. The full 2021 CCE Index results are available on the CCE Index web portal: https://cceindex.kapsarc.org