In Sweden, Early Childhood Education and Care is a right for every child and children in need of special support have access to these provisions in inclusive mainstream settings. National evaluations show great quality variations in special educational support in preschools and schools across the country. A Multicenter Research School with 10 PhD students from four Universities and international partners has been funded (2018- 2021) by the Swedish Research Council to develop knowledge in early intervention. Preschool/school environments are assessed and tailored interventions at unit or child level are developed. The projects are built on previous research and identified needs in research and practice. The theoretical framework for the Research School will be described, results from a systematic review of previous research and specific plans for various topics (engagement, early literacy, expressive language development, socio- emotional development, self-regulation) will be presented and linked to the theoretical framework.