The principal decision-making body for the Convention is the Conference of the Parties (COP) which meets once every three years. For most of the legally binding Agreements, instead of a COP, there is a Meeting of the Parties or MOP (the exception is the Wadden Sea Seals Agreement which is overseen by the Wadden Sea Board made up of representatives of the three Range States, Denmark, Germany and the Netherlands); the MOP meets every three or four years, depending on the provisions of each Agreement agreed by the Parties. MOUs have Meetings of the Signatories (MOS).

The various decision-making bodies of the CMS Family instruments review progress made and challenges encountered during implementation, and decide on the priorities for the next intersessional period. Where applicable, they also review the instrument’s finances and set a budget.

The roles and functions of the CMS COP are outlined in Article VII of the CMS. The main aim of the COP is to assess and agree upon amendments to the Appendices and to adopt resolutions. The COP additionally establishes and reviews the financial regulations of CMS, adopts the budget for the following three years and reviews the implementation of CMS. In particular, the COP may review and assess the conservation status of migratory species and the progress made towards their conservation.

The COP is presided over by a Chair, usually the representative of the Host Government and is overseen by a Bureau made up of the elected officers of the meeting, the Chair of the Standing Committee and the Scientific Council and supported by the Secretariat. Decisions – such as the election of officers, the adoption of the agenda and the Rules of Procedure, the establishment of Committees and Working Groups, and at the end of the COP, the adoption of resolutions are taken by the Plenary, that part of the meeting attended by all delegates. Detailed discussion of the COP’s general business is conducted by the Committee of the Whole; some specialized business such as the budget is referred to a dedicated Committee or Working Group. Committees and Working Groups that meet only during the course of a meeting of a decision- making body are called “in-session Working Groups”; those that carry on after the close of the meeting are called “intersessional Working Groups”. These report their findings and make their recommendations either to the next meeting of the subsidiary of the decision-making body.

Meetings of the decision-making bodies follow more or less the same pattern as those of CMS, but tend to be much smaller in scale, reflecting the smaller membership of the instruments in comparison with the parent Convention.