Schools as learning communities have been recommended by the European Commission as an effective model to support school quality and development. Aiming at studying how these schools are achieving such positive results, this article focuses on the analysis of a particular classroom intervention called "interactive groups". A five-year longitudinal case study has been conducted in a socio-economically deprived urban school under the European Union-funded large-scale research project INCLUD-ED: Strategies for Inclusion and Social Cohesion in Europe from Education. Descriptive and interpretative analysis was conducted based on quantitative indicators on school performance in mathematics and including qualitative data from classroom observations and interviews with pupils, parents and teachers. Particularly, the authors aim to explore in which ways and under which conditions dialogic interactions take place in culturally diverse small groups when doing interactive groups in mathematics. Data on school performance in mathematics shows a sustainable improvement over time. Families, teachers and students seem to link the interactions in interactive groups with an improvement in their relationships in the school and in the community. The authors conclude that the dialogical approach identified in interactive groups among students, teachers and parents improves students' achievement and increases the potential of community-based mathematical interventions in primary classrooms. Lessons learned from this study have informed educational policies in Europe.