Publisher Summary This chapter deals with the kinetic studies that illustrates time-resolved laser fluorescence spectroscopy for atomic and molecular excited states. Radiative deexcitation and collisionally induced excitation transfer processes involving various atomic, and molecular states are of great fundamental and practical interest; they play a major role in the understanding of such systems as gas lasers, stellar atmospheres, molecular formation in astrophysics, gaseous plasmas up to thermonuclear conditions, and ionosphere physics. This chapter gives a brief review of the main other direct and indirect methods that have been used for such studies. It also illustrates the experimental aspects of time-resolved laser fluorescence spectroscopy: dye lasers and photon detectors, electronics and data acquisition systems, deconvolution of the time response of the detection systems, and finally, the important-and often somewhat vexing-problem of extracting from the raw experimental data the kinetic coefficients for deexcitation and/ or transfer between the various excited states. Moreover, this chapter explores an examination of the application of these laser techniques to atomic and molecular physics. Finally, this chapter concludes that Laser fluorescence spectroscopy is a fast-growing and important subject in the near future.