1. Structures; 2. Metre Convention; 2.1. The Metre Convention; 2.2. The BIPM; 2.3. The MKS system; 2.4. The SI Brochure; 3. BIPM: the first 75 years; 4. National structures: The National Metrology Institutes (NMIs); 4.1 National Metrology Institutes; 4.2. NMI science; 5. Traceability: The birth of accreditation; 5.1. Traceability; 5.2. Accreditation bodies; 5.3. ILAC; 5.4. A National Measurement System; 5.5. Definitions of traceability; 6. Regional Metrology Organisations; 6.1. The birth of RMOs; 6.2. RMOs today; 6.3. Equivalence of national measurement standards; 7. Mutual recognition of NMI standards: the CIPM MRA; 7.1. The significance of the CIPM MRA; 7.2. Launch; 8. The essential points of the CIPM MRA; 8.1. Objectives; 8.2. Technical competence; 8.3. Comparisons and quality systems; 8.4. The NMIs commitment; 8.5. Associates of the General Conference; 8.6. The Key Comparison Database (KCDB); 9. Take up of the CIPM MRA; 9.1. Regulators and the CIPM MRA; 9.2. A market for NMI calibration services; 9.3. Consequences for NMI services; 10. Other metrology bodies; 10.1. The World Metrology System; 10.2. Accreditation and ILAC; 10.3. The importance of MRAs; 10.4. Measurement Accreditation and Standardization; 11. Closing comments