The invention relates to photopolymerizable compositions containing an oxonol dye, which compositions cure by exposure to ultraviolet and/or visible radiation and whose visible color is substantially reduced during exposure. More particularly, the invention pertains to photopolymerizable compositions comprising a pyridin-2,6-dione oxonol dye in an admixture of a polymerizable component and a photopolymerization initiator. Such compositions find use as adhesives, coatings, and the like. The disappearance of the visible color of the oxonol dye acts as an indicator of full cure of a photopolymerizable composition.