Publisher Summary The quality of cheese is determined by its (1) flavor (taste and aroma), (2) rheological properties, referred to as body and texture including parameters such as hardness, cohesiveness, sliceability, meltability, and stretchability, and (3) visual appearance. The flavor of cheese has been the subject of scientific investigation for nearly a century. This chapter illustrates that the cheese flavor is due to the correct balance and concentration of a wide range of sapid and aromatic compounds leading to the “component balance theory.”All cheese varieties that have been studied contain essentially the same range of sapid compounds. Their flavors differ owing to the absolute and relative concentrations of these compounds. Cheese flavor is assessed by subjective sensory methods. A key task in the chapter is the establishment or recognition of the flavor characteristic of a variety and the development of a vocabulary of terms with which to describe cheese flavor. This chapter describes the biochemical pathways for the formation of known sapid and aromatic compounds in cheese. Particular attention is focused on the catabolism of amino acids.