An international team at CERN's synchrocyclotron carries out the first direct measurement of the muon's anomalous magnetic moment, known as "g-2". The experiment's original idea comes from Leon Lederman; the team that designs and runs it, led by Francis Farley, is composed of Georges Charpak, Théo Müller, Johannes Cornelius Sens, and Antonino Zichichi, formalized in 1959 based on the two discoveries that made it possible to track the muon's polarization in flight (the parity-violation experiments of Garwin-Lederman-Weinrich and Friedman-Telegdi, both from 1957). Valentine Telegdi joins the project as a visiting collaborator, contributing his expertise in muon polarization physics. By storing polarized muons in a six-meter magnet for up to a thousand cyclotron periods, the team measures the anomalous value a = (g-2)/2 with 2% precision relative to the theoretical value predicted by quantum electrodynamics (QED), confirming that the muon behaves as a "heavy electron" and experimentally validating QED for a second generation of leptons. The experiment inaugurates a measurement program repeated with increasing precision for more than sixty years — at CERN itself, later at Brookhaven, and today at Fermilab — and remains, to this day, one of the most sensitive precision tests for searching for physics beyond the Standard Model.