Cover picture: Confocal fluorescence microscopy images of giant unilamellar vesicles (GUV) of DPPC/DLPC/cholesterol. Each sample contains two fluorescent dyes: Dil-C20:0 (orange) partitions into rigid, ordered phases; Bodipy-PC (green) partitions into fluid phases. GUV having a single phase appear overall orange or green, depending on dye quantum yield. Coexisting phases show both orange and green domains. Cholesterol concentration varies along the vertical axis from 0 (bottom) to 16.5 mol%. DPPC content varies from 0 (left) to 100%. Scale bars, 5 µm. See the article by Feigenson and Buboltz on p. 2775.