This paper forms part of a research project that aims to characterise best practices in highly effective schools in the Autonomous Region of the Basque Country (ARBC). The aim is for the best practices identified to serve as points of reference when designing improvement plans to be implemented in all schools in the ARBC, with the advice and support of the education inspectorate. Highly effective schools are identified through the results of the Diagnostic Assessments carried out by the Basque Institute for Research and Evaluation in Education (ISEI-IVEI) of all primary and secondary schools in the ARBC. Multilevel statistical modelling and Hierarchical Linear Models were used to select 32 highly effective schools, with highly effective being taken to mean any school with higher-than-expected student results after adjusting for the effect of contextual factors. Eighty-three interviews were conducted with management teams, educational advisors and inspectors at each of the selected schools. This paper presents the results obtained in relation to how attention to diversity is organised. The practices identified included, among others, inclusive actions such as support teaching in ordinary classrooms, the splitting up of classroom groups, the formation of heterogeneous groups and the conceptualisation of the support provided as a shared teaching responsibility.