Standardisation and standards are common in the modern world, including in social work. This article focuses on social workers who implement the assessment tool Children’s needs in focus (Barns behov i centrum BBIC) in Swedish social work with children and families. Inspired by ‘siblings’ in the UK, the National Board of Health and Welfare has developed and supported the implementation of the BBIC. From the start, the implementation strategy was to engage well-educated and experienced social workers as educators. The article studies these educators (standardizers) as mediators between national imperatives and local practice during the implementation of the BBIC in the social services. Based on interviews with 10 BBIC educators, three standardizer roles were identified: the instrumental, the adaptive and the transformative. These roles affect the practice of social work in potentially different ways.