Neither the first round of Nationally Determined Contributions (NDCs) nor currently implemented climate policies are on track to meeting the Paris Agreement’s objectives. Parties are expected to increase their ambition and produce new NDCs covering the post-2030 period. The design of a multi-dimensional set of policy measures that comprise countries’ climate policy agendas is supported by equally diverse integrated assessment modelling (IAM) activities. Notwithstanding the recent progress in the IAM literature and scenario space, the modelling world has fallen short of its promise to include non-scientists in its process; to account for individual choices and lifestyle changes that are indirectly narrated as assumptions not interacting with the vividly modelled technology-economy-environment-policy flows; and to place climate action as a cross-cutting theme in the sustainability spectrum. IAM COMPACT will support the assessment of global climate goals, progress, and feasibility space, as well as the design of the next round of NDCs and policy planning beyond 2030 for major emitters and non-high-income countries. We will use a diverse ensemble of models, tools, and insights from social and political sciences and operations research, and will integrate bodies of knowledge to co-create the research process and enhance transparency, robustness, and policy relevance. We will explore the role of structural changes in major emitting sectors and of political, behaviour, and social aspects in mitigation; quantify factors promoting or hindering climate neutrality; and account for extreme scenarios, to deliver a range of global and national pathways that are environmentally effective, economically viable, politically feasible, and socially desirable. In doing so, we will fully account for COVID-19 impacts and recovery strategies, and align climate action with broader sustainability goals, while developing technical capacity and promoting ownership in non-high-income countries.