Bioluminescence (BL) has revealed an extremely useful analytical tool enabling ultrasensitive detection in biotechnological applications. Following the discovery of luciferin and luciferases, molecular biology techniques allowed the cloning of several luciferases and photoproteins. Among most used BL reporters, we find firefly and click-beetle luciferases, bacterial luciferase, Renilla, Gaussia, and Cypridina luciferases, and calcium-activated photoproteins. According to the specific bioluminescent protein, different substrates and protocols must be applied in the experimental procedure for BL measurement. By conjugating (either chemically or by molecular biology techniques) bioluminescent probes to specific targets, it is in fact possible to track a wide range of events and analytes. To aid investigators in the choice and applications of reporter genes, the materials and methods required for BL measurements and experimental protocols are described.