This chapter discusses some of the key concepts related to the use of starchy grains or grain fractions in food products. It is not a review of starch chemistry, but uses case studies to illustrate the following key ideas: (1) there are immense genetic variations in the properties of starch, both at the species level (e.g. comparing maize with rice) and at the genotypic level (comparing accessions or varieties within a species); (2) starch may be subjected to chemical and physical modifications and the impact of these modifications depends on the properties of the native starch; and (3) formulation (e.g. pH and salt content) and processing conditions (e.g. the thermal profile) will further modify the starch properties of the resulting food product. In terms of food processing, the primary manifestation of the role of starch is in texture, which influences the sensory acceptability of the product. Regarding functional foods, starch may act as a carrier for bioactive molecules and may interact with such molecules in further modifying the texture or nutritional attributes. Within this complicated system, we need an understanding of how to measure and understand the basic properties of starch as a food material. Starch has its most fundamental role as the primary energy source in human diets, so it is essential to understand the basic concepts of digestibility and the interaction of starch with amylolytic (starch-degrading) enzymes.