Ciro Santilli Sponsored by National Academy of Sciences, located in Long Island.
Some photos at: www.nasonline.org/about-nas/history/archives/milestones-in-NAS-history/shelter-island-conference-photos.html on the website of National Academy of Sciences, therefore canon.
This is where Isidor Rabi exposed experiments carried out on the anomalous magnetic dipole moment and Willis Lamb presented his work on the Lamb shift.
It was a very private and intimate conference, that gathered the best physicists of the area, one is reminded of the style of the Solvay Conference.
QED and the men who made it: Dyson, Feynman, Schwinger, and Tomonaga by Silvan Schweber (1994) chapter 4.1 this conference was soon compared to the First Solvay Conference (1911), which set in motion the development of non-relativistic quantum mechanics.
Followup to the Shelter Island Conference, this is where Julian Schwinger and Richard Feynman exposed their theories to explain the experiments of the previous conference.
Julian made a formal presentation that took until the afternoon and bored everyone to death, though the mathematics avoided much questioning.
Feynman then presented his revolutionary approach, which he was unable to prove basic properties of, but which gave correct results, and people were not very happy.