As the world faces the risks of dangerous climate change, policy-makers, industry and civil society leaders are counting on Integrated Assessment Models (IAMs) to inform and guide strategies to deliver on the objectives of the Paris Agreement (PA). ENGAGE rises to this challenge by engaging these stakeholders in co-producing a new generation of global and national decarbonisation pathways. These new pathways will supplement natural science, engineering and economics, traditionally represented in IAMs, with cutting-edge insights from social science in order to reflect multidimensional feasibility of decarbonisation and identify opportunities to strengthen climate policies. The pathways will be designed to minimise overshoot of the temperature target and analyse the timing of net-zero emissions to meet the Paris temperature target and reduce the reliance on controversial negative emissions technologies. In addition, they will link national mitigation strategies of major emitters with the PA's objectives, integrate potential game-changing innovations, and advance conceptually novel approaches to architectures of international climate agreements. ENGAGE will also quantify avoided impacts of climate change, co-benefits and trade-offs of climate policy, and identify the biggest sectoral opportunities for climate change mitigation. In ENGAGE, we will set new standards of transparency for global and national IAMs. The new pathways will be developed in an iterative global and national stakeholder process and a consortium of leading global and national IAMs and social scientists. This co-production process ensures that the pathways are credible, legitimate, and rooted in concrete policy and industry experience, making them relevant to inform the 2023 global stocktake and feed into the mid-century strategies of major emitters.