The School was founded in 1891 and became established as the Wellington Diocesan School in 1912. The school was an autonomous body under the aegis of the Synod of the Wellington Diocese, having the Bishop of Wellington an ex officio member of the Board of Trustees.

The school (known also as Nga Tawa) has continued to operate as a boarding and day school for students catering for the needs of families from all districts of New Zealand and overseas, wanting an Anglican School education in a rural boarding setting. Because of its affiliation to the Diocese of Wellington of the Church of Aotearoa New Zealand and Polynesia, Nga Tawa students receive education as an extended family group. The school atmosphere emphasises Christian standards, values and observances as is customary in Anglican Diocesan boarding schools. Integral to this education is the use of the Chapel as a place of regular prayer, worship and instruction.

Nga Tawa caters for students living in the boarding establishment with which it is intimately associated and it is conducted in order that all tuition, religious, recreational and cultural activities provided for all students are organised so that day students can, as far as possible, share the advantages offered to boarding students. Accordingly it has been the policy of the school to accept only a limited number of day students on the clear understanding that such students will as far as possible follow the routine and share in the activities of boarding students.

In addition to the educational philosophy outlined above the special character provisions of the integration agreement require that the school places a particular emphasis on Music, the Arts and Recreation. In 2008 Nga Tawa Diocesan School became the school's official Ministry of Education name.