Composite two-dimensional (2D) polystyrene (PSt) arrays, composed of three types of PSt particles, red fluorescent, green fluorescent, and nonfluorescent, were prepared from an aqueous suspension These arrays form as a result of water evaporation and capillary forces. Using fluorescence microscopy and phase-contrast microscopy, we observed several interesting types of light propagation phenomena in single layers of the array, including anisotropic light propagation, an additive effect for light intensity, and a novel switch function. These characteristic light propagation phenomena indicate some of the possibilities of the 2D array as a photonic device.