Charter/Sponsoring Members are signatories to the NARSTO Charter. They are voting members of the Executive Assembly, and provide financial and in-kind support for NARSTO activities.

Participating Partners are generally drawn from the university and research contractor communities. They are Charter signatories, and each partner brings valued expertise and experience to NARSTO program planning and assessment activities. However, they cannot serve as members of the Executive Assembly and as official members of the Science & Resource Planning Group. Participating Partners are responsible for their own expenses associated with participation in NARSTO planning functions and attendance at NARSTO meetings.

Affiliated Partners are organizations who are located outside North America or whose scientific expertise is outside the scope of NARSTO, but nevertheless have related interests. Such organizations may request membership, and upon approval by the NARSTO Executive Steering Committee, will be granted membership as Affiliated Partners. Affiliated Partners can provide advice and guidance to NARSTO, but they do not sign the Charter. Affiliated Partners also pay their own travel and other expenses when participating in NARSTO activities.