The series of 9-acridy] derivatives of aromatic amines have been investigated as fluorescent probes for monitoring the progress of free-radical polymerization. This study on the changes in the fluorescence intensity and spectroscopic shift of specific compounds was carried out during thermally initiated polymerization of methyl methacrylate and photoinitiated polymerization of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate-1-methyl-2-pyrrolidonone mixture. The purpose of this investigation was to find a relationship between the changes in the shape and intensity of fluorescent probes and the degree of monomer conversion into a polymer.