This article provides data about qualitative and quantitative research that was executed in juvenile detention centres in The Netherlands in the framework of the EU-funded Restorative Justice in Europe project. The results of a survey amongst 75 staff members are presented. Special attention is paid to the restorative handling of internal conflicts and crimes within the detention centre. Restorative Justice Nederland, executing this research, also developed a self-assessment tool for prisons, the Organisational Maturity Grid Restorative Practices, that can be used to assess how ‘mature’ restorative practices are within an organisation. Based on this maturity grid and the data of the research advice is provided on how restorative practices within juvenile detention centres can be brought to the next level.