Discovering universal laws governing protein folding and stability may profoundly impact different aspects of human life, ranging from industrial applications of proteins to medicinal biotechnology for the prevention and treatment of diseases. Despite a considerable number of investigations, including theoretical, computational, and experimental studies on the sequence, structure, and function of proteins, the protein folding problem is still an unanswered question. Protein folding is a fast process that occurs on a time scale of a few microseconds to a few seconds. Folding kinetics depends on multiple factors, including protein sequence and external conditions, and can be studied using various spectroscopic methods combining different unfolding/refolding techniques. In this chapter, we attempt to discuss experimental aspects of protein folding kinetics. The methodology, data analysis, and interpretation of kinetic data in protein folding studies are discussed.