There are two main forms of school evaluation: Schools are required to conduct ongoing school self-review and external school reviews are conducted by the Education Review Office (ERO) on average every three years. The approach to school evaluation is collaborative, characterised by good levels of trust between schools and ERO. School self-review is at the heart of quality assurance and improvement processes. The basic premise is that schools are best placed to analyse their own contexts and that ERO can provide an external perspective to validate or challenge the schools’ own findings. ERO’s review approach is differentiated based on school needs, the composition of ERO teams is credible and review procedures are sensitive to cultural diversity. However, there are still tensions between the improvement and accountability functions of school evaluation. Schools’ own annual reporting to the Ministry of Education does not seem well connected to other aspects of school evaluation. There is also an ongoing need to provide professional learning and support for teachers, school leaders and Boards of Trustees to conduct effective school self-review and use evaluative data effectively for improvement.