Chalcones, flavanones, dihydrochalcones, and aurones are categorized into minor flavonoids. Compared to major flavonoids, these constituents are limited in relative abundance in nature and seem almost like unwanted byproducts in the biosynthetic system of plants. It should be true that they play a prominent role in the management of plant life, such as growth regulation, pigmentation, self-defense, plant-herbivore interactions, etc., but their significance remains unclear. Chemically, they are unique subclasses of flavonoids in the view of their structural diversity. This chapter deals with minor but interesting chalcones, flavanones, dihydrochalcones, and aurones.