Double-Luciferase Reporter Assay Kit provides an efficient means of performing dual-reporter assays. In the assay, the activities of firefly (photinus pyralis) and renilla (sea pansy) luciferases are measured sequentially from a single sample. The firefly luciferase reporter is measured first by adding Luciferase Reaction Reagent to generate a stable luminescent signal. After quantifying the firefly luminescence, this reaction is quenched, and the renilla luciferase reaction is simultaneously initiated by adding Luciferase Reaction Reagent II to the same tube.