Methods, reagents, kits and systems are disclosed for determining an analyte in a sample suspected of containing the analyte where all reagents are soluble in aqueous solution. One assay method includes treating a sample suspected of containing the analyte under conditions such that if the analyte is present, an activator is brought into reactive configuration with a chemiluminescent compound to activates it. The sample is also treated with an agent to reduce signal not related to analyte. Finally, the sample is treated with a trigger solution thereby producing light from the activated chemiluminescent compound. No reagents are associated with a surface or other solid phase.