The 2027 Gordon Research Conference "Interfacial and Droplet Reactivity: Mechanisms, Measurement, and Applications" starts from the rapidly growing evidence for reaction acceleration in droplets and asks which droplet features (size, preparation, charge) matter, how experimental conditions should be reported, and how droplet synthesis and catalysis can scale. Mechanistic sessions examine the role of the interface and of excess charge, new interfacial spectroscopies and the theory needed to interpret them, pH and strong electric fields that can make or break bonds or drive redox reactions, and reactivity at oil-water emulsions and other hydrophobic-water interfaces, including links to emulsion stability and biomolecular condensates. Applications span synthesis, energy and environmental chemistry, in a dialogue between physical, organic and synthetic chemists, atmospheric scientists and theorists aimed at a molecular understanding of interfacial reactivity. The five-day meeting combines talks on unpublished work with extended discussion, poster sessions open to all career stages, and communal meals and free afternoons for informal exchange; attendance is by application.