Chemiluminescent bioassays for the presence or concentration of an analyte in a sample use 1,2-dioxetanes as substrates for the enzyme of an enzyme complex that bind to the analyte. The chemiluminescence obtained from the decomposition of the dioxetane triggered by the enzyme through the formation of the corresponding 1,2-dioxetane oxyanion of the enzyme complex is enhanced by the addition of TBQ as an enhancement agent. Other polymeric quaternary onium salts can be used as enhancement agents in conjunction with enhancement additives which improve the ability of the enhancement agent to form hydrophobic regions in the aqueous sample, in which regions the 1,2-dioxetane oxyanion and its chemiluminescent decomposition products can be sequestered. A kit for performing such assays is also provided.