Circular Economy (CE) is gaining momentum and its diffusion in manufacturing companies remains a key element to be addressed. Indeed, the principles and practice of circularity can enhance sustainability in the manufacturing sector, but changes are required in organizations in order to fully embrace this paradigm. Therefore, several assessment models have been proposed to quantitatively measure CE performance, yet covering niche aspects, whereas a holistic perspective is usually neglected. In addition, there is significant scope to improve the elements composing the big picture through delineating where possible improvements might occur and this can be provided through an evaluation of the current status of a manufacturing company in respect to the optimum or reference model. Therefore, the goal of this contribution is to create the building blocks for a maturity model assessment proposing a complete and exhaustive maturity scale supporting companies in clarifying strategic objectives towards circularity in manufacturing. This goal has been achieved through a review of the scientific literature and a validation exercise performed through two workshops in which practitioners and researchers have been involved. This mixed-methodology allowed to strengthen the results obtained.