ISASA  represents its members and provides them with more than 50 services to protect their interests, promote best practice and support quality education and school sustainability.

The benefits of ISASA membership are broadly divided into four categories:

1. Providing a community of colleagues.
2. Simplifying a school’s life.
3. Promoting schools’ interests and protecting their rights.
4. Strengthening schools’ sustainability and saving them money.

The association publishes a brochure titled Why Belong to ISASA? that examines these member benefits in greater detail.

To apply for membership, a school should complete the ISASA Membership Application Form. All ISASA member schools must also agree to abide by the ISASA Conditions for Membership.

ISASA levies member subscriptions on a per pupil, per annum basis, and on a six-category sliding scale determined by the socio-economic circumstances of the member school. In effect, the lower the school's income the less ISASA charges the school for membership. The ISASA Subscription Rates for 2013 are available for download.

The cost of ISASA membership can often be totally offset against what a school saves by using ISASA’s services.