System, including methods, apparatus, compositions, and kits, for assays with an emulsion including capsules. A method of performing an assay is provided. In the method, an aqueous phase may be provided. The aqueous phase may include a sample and an effective concentration of one or more skin-forming proteins. An emulsion may be formed. The emulsion may include droplets of the aqueous phase disposed in a nonaqueous continuous phase. The emulsion may be heated to create an interfacial skin between each droplet and the continuous phase, to transform the droplets into capsules. Assay data related to the sample may be collected from the capsules.