Special issue of ACS Photonics published today, “Strong Coupling of Molecules to Cavities”. Together with Francisco Garcia Vidal and Javier Aizpurua I guest-edited this special issue, based on the workshop we held in San Sebastian, SCOM16. The special issue can be found at: http://pubs.acs.org/toc/apchd5/5/1, and provides a wonderful snapshot of the field of strong coupling with organic molecules. SCOM18 will be held in Eindhoven this April https://www.scom2018.eu/home.