Most species are prostrate or climb by tendrils. They are annual or perennial herbs native to temperate and tropical areas. No member of the family tolerates frost or cold soil. Most species are extremely sensitive to temperatures near freezing, a factor that limits their geographic distribution and area of cultivation. The family includes such economically important food plants as pumpkin, cucumber, gherkin, watermelon, muskmelon, summer squash, winter squash, chayote, cassabanana, squash, and gourd. Cucurbits have a generally low nutrient content; one exception is the winter squash (certain cultivars of Cucurbita maxima, C. moschata, C. pepo, etc.).

Members of the family are fast-growing, with long-stalked, palmate leaves that alternate along the stem. Most species have unisexual flowers, which are borne in the leaf axils and have five white or yellow petals. At the side of the leafstalk in annual species there is a simple, often branched, spirally coiled tendril. It is generally regarded by most botanists to be a modified shoot. There are five sepals in each flower; male flowers have up to five anthers, often fused or joined in a complex way, and female flowers usually have three carpels. The fruit in most species is a fleshy, many-seeded berry with a tough rind, often attaining considerable size. The seeds are flattened and sometimes have beautiful wings.