This study aims to provide a comprehensive understanding of belonging in early educational institutions based on key findings developed within the international project Politics of belonging: promoting children's inclusion in educational settings across border (85644). The research questions are: What are the main empirical and theoretical contributions to the understanding of belonging in early childhood institutions? and What kinds of critical factors regarding belonging can be identified? This study applies Yuval-Davies' theory about the politics of belonging. The data consists of key findings from 28 publications from the aforementioned project. Theoretically, the project provides a novel perspective regarding processes related to belonging in early educational institutions. Such processes involve transgressing, defending and defining borders dictating who is inside or outside these communities. Empirically, the project contributes knowledge about how belonging is performed in practice. Belonging manifests as a joint enterprise involving children, educators, parents and policymakers; it is also multifaceted and powerladen. This study delineates critical elements of children's belonging. On a micro level, these elements require specific forms of agency amongst children and specific forms of responsibility amongst educators, which exert consequences on a macro level. The discussion concludes with five recommendations regarding policy and practice.