Founded in 1888, the Secondary Schools' Conference brought together for the first time the heads and assistants of New Zealand high schools. Successive changes in secondary education produced alterations in the organisation's title and membership until 1951 when the present Post-primary Teachers' Association arose from the union of interests of teachers in the technical and other secondary schools.

With a current membership of nearly 5,600, the association speaks for the overwhelming majority of full-time teachers in the country's secondary system. A national executive, served by a small administrative staff, deals with an immense variety of teacher concerns and problems. Policy is forged at annual conferences attended by delegates from each branch, a branch consisting of the staff of an individual school. The association and its predecessors have had much to say on educational policy. Since 1920, for instance, it has been engaged in formal national salary negotiations. Further, there has been continuous activity in a great number of other matters of vital educational importance, including: technical education, Maori education, high ability pupils, slow learners, delinquency, television, agricultural education, standards and prescriptions for individual subjects, examination organisation and policy, the intermediate school system, personal teacher problems and rights, teacher grading and inspection, regulations, building standards, and literally scores of other matters of concern to teachers and pupils. The association publishes a monthly magazine, The Journal.