Abstract: Chemiluminescent electron-rich aryl-substituted 1,2-dioxetane compounds are disclosed in which the aryl group is poly-substituted with suitable electron-donating groups such that the light-emitting pattern of the molecule results in a very high luminescent count, thus providing for a sensitive and precise assay for haptens, analytes, polynucleotides and the like. These substituted aryl-containing 1,2-dioxetane compounds can be used as direct labels in an immunoassay or when derivatized with an appropriate leaving group, can be used as a substrate for a enzyme immunoassay. The unusual chemiluminescence of the compounds allows the timing of the luminescent reaction to be exactly controlled.