Although with different origins and initial concerns, the Social and Solidarity Economy (SSE) and the Circular Economy (CE) can complement each other to transform the current development model. CE could help to address biophysical goals of ecological sustainability and the reduction and closure of material cycles; the SSE would serve to prioritize people's needs and social equity. However, we have to bear in mind that while the SSE in its practical experiences has already tended to be concerned with ecological sustainability, the CE has not done the same with redistributive or social equity issues. In the last decade, CE is receiving increasing attention and is spreading rapidly supposedly as a solution for sustainable development. However, the majority of its current practices lack a comprehensive and transformative approach, and instead, they focus mainly on technological efficiency and competitiveness without giving the deserved attention to sufficiency and cooperation issues. Therefore, in this text we analyze how the CE should be enriched by the postulates of the SSE if we are to seek an equitable and sustainable transition. We studied the case of REAS-Euskadi in the Basque Country, and the Chambers of ESS APRES-GE and APRES-VD in Western Switzerland on topics such as: the expanded understanding of the 9Rs approach; the characteristics of the new circular business models, the principles of the SSE, such as cooperation and not-for-profit, among others.