Reprinted in The Physical Review - the First Hundred Years, AIP Press (1995) 167.
Selected Papers on Quantum Electrodynamics, editor J. Schwinger, Dover Publications, Inc., New York (1958) 143.

Motivation
Attempts to evaluate radiative corrections to electron phenomena have heretofore been beset by divergence difficulties, attributable to self-energy and vacuum polarization effects. Electrodynamics unquestionably requires revision at ultra-relativistic energies, but is presumably accurate at moderate relativistic energies. It would be desirable, therefore, to isolate those aspects of the current theory that essentially involve high energies, and are subject to modification by a more satisfactory
theory, from aspects that involve only moderate energies and are thus relatively trustworthy. This goal has been achieved by transforming the Hamiltonian of current hole theory electrodynamics to exhibit explicitly the logarithmically divergent self-energy of a free electron, which arises from the virtual emission and absorption of light quanta. The electromagnetic self-energy of a free electron can by ascribed to an electromagnetic mass, which must be added to the mechanical mass of the electron.
Indeed, the only meaningful statements of the theory involve this combination of masses, which is the experimental mass of a free electron. It might appear, from this point of view, that the divergence of the electromagnetic mass is unobjectionable, since the individual contributions to the experimental mass are unobservable. However, the transformation of the Hamiltonian is based on the assumption of a weak interaction between matter and radiation, which requires that the electromagnetic mass be
a small correction (~ (e^{2}/h c)m_{0}) to the mechanical mass m_{o}. Summary The simplest example of a radiative correction is that for the energy of an electron in an external magnetic field. The detailed application of the theory shows that the radiative correction to the magnetic interaction energy, corresponds to an additional magnetic moment associated with the electron spin, of magnitude / = (1 / 2 ) e^{2}/h c = 0.001162. It is indeed gratifying that recently acquired experimental data confirm this prediction. (Extracted from the introductory part of the paper.).

Related references See also J. E. Nafe, E. B. Nelson, and I. I. Rabi, Phys. Rev. 71 (1947) 914;
D. E. Nagle, R. S. Julian, and J. R. Zacharias, Phys. Rev. 72 (1947) 971;
G. Breit, Phys. Rev. 71 (1947) 984;
H. A. Bethe, Phys. Rev. 72 (1947) 339;
W. E. Lamb and R. C. Retherford, Phys. Rev. 72 (1947) 241;
J. E. Mack and N. Austern, Phys. Rev. 72 (1947) 972;
P. Kusch and H. M. Foley, Phys. Rev. 72 (1947) 1256;

Particles studied

e^{–}

mom

e^{+}

mom

Record comments
First theoretical calculation of g-2 for the electron.