The miscibility of two amphiphilic calix[4]arenes, p-dodecanoylcalix[4]arene and 25,27-bis-dihydroxyphosphoryloxy-tetradodecanoyl-calix[4]arene, in mixed monolayers with four phospholipids, 1,2-dipalmitoylsn-glycero-3-phosphatidic acid, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1,2-dipalmitoyl-snglycero-3-phosphocholine (DPPC), and 1,2-dipalmitoyl-sn-glycero-3-phosphoserine, has been studied by the Langmuir film method and Brewster angle microscopy (BAM). For p-dodecanoylealix[4]arene, the mixed layers are immiscible except for those with high mole fraction of DPPC. For 25,27-bis-dihydroxyphosphoryloxy-tetradodecanoyl-calix[4]arene, the mixed layers are miscible in all proportions. Studies of the additivity of the mean molecular areas show strong deviation from ideal behavior. The BAM images show that film morphology in mixed layers differs from single-component films.