The Commonwealth Secretariat is the main intergovernmental agency and central institution of the Commonwealth of Nations. It is responsible for facilitating co-operation between members; organising meetings, including the Commonwealth Heads of Government Meetings (CHOGM); assisting and advising on policy development; and providing assistance to countries in implementing the decisions and policies of the Commonwealth.

The Commonwealth of Nations, often simply referred to as the Commonwealth, is an international association of 56 member states, the vast majority of which are former territories of the British Empire from which it developed. They are connected through their use of the English language and historical-cultural ties. The chief institutions of the organisation are the Commonwealth Secretariat, which focuses on intergovernmental aspects, and the Commonwealth Foundation, which focuses on non-governmental relations among member states. Numerous organisations are associated with and operate within the Commonwealth.