Publisher Summary This chapter describes the chemical assessment of automotive clearcoat weathering. The top, unpigmented layer of a modem automotive paint job is known as a clearcoat. The selection process for materials for use as a clearcoat is an arduous process involving multiple tests. The chapter describes photoacoustic and microspectroscopic technologies applied in the infrared, and UV as means to assay the changes in chemical composition and UV protection produced by the clearcoat in complete automotive paint systems. The desired performance includes resistance to chemical degradation in a photo-oxidative environment. Another performance requirement is the shielding of all under layers from destructive radiation. The chapter proposes variants from IR and UV spectroscopies that are accepted in the routine analysis environment. The focus of this chapter is on the characterization of the clearcoat layer as part of a full paint system as it weathers. PAS-IR and UV microspectroscopy are useful tools for the chemical evaluation of full paint systems. The results are encouraging and it hopes to see them accepted as coatings ranking and evaluation methods.