This paper reports the construction of a teacher rating instrument designed to monitor the social and emotional development of school age children and young people (4-17 years). The instrument was developed by reviewing previously implemented checklists to build an extensive list of behavioural and emotional criteria and through the use of focus groups to establish the views of key stakeholders. The criteria were categorized according to three areas: conduct, emotion and learning. The initial instrument of 21 items was piloted and amended accordingly. The final trial of the instrument was carried out on a sample of 7285 pupils from a cross-section of UK schools. A principal component factor analysis confirmed the division of the scale into three factors. The instrument was supported by trends showing that the distributions were different for different types of schools and between males and females. The final version of the instrument was amended to include 15 items, five in each category (conduct, emotion, learning), all expressed positively on a six-point scale. The scale is a useful tool for providing a basis for a strategic discourse between staff in planning approaches to the emotional and behavioural development of students in school.