This chapter reviews the methods for the determination of equilibrium and rate constants of drug–receptor binding. It describes Hill, Scatchard, and Bjerrum methods for the determination of equilibrium constants and degree of cooperativity for a ligand binding to multiple receptor sites. It also describes the Lineweaver–Burk method that is used to characterize a type of mutual antagonism for one receptor binding site for a series of ligands. Pharmacological (based on an organ’s reaction to a drug) and radioligand (based on the concentration of a labeled compound) methods are explained, and their advantages and disadvantages are compared. Additionally, the kinetics of competitive ligand binding, relaxation methods for drug–receptor binding rate constant measurement, and methods for the kinetics study of conformational changes in protein–ligand complexes are considered.