Entellus langurs are not as sociable as some other monkeys are. Although they live in groups of 8 to 125 individuals, they rarely band together for protection, instead seeking out solitary sanctuary. They can live in one of several social arrangements, but the single-male group is the most common. In these groups, there is one adult male living among several adult females and their offspring. Competition for the single-male position can be fierce.
Entellus langurs eat a mostly vegetarian diet.
Leaves are their principal food, but they also eat flowers, fruit, and seeds, and occasionally insects and fungi. Although quiet, the entellus langur can be an extremely active monkey. They are most active in the early morning, when they begin their first food forage of the day, and in the late afternoon, their second foraging time. During the hot afternoons they nap in a shady spot, and at night they sleep on i the edges of tree limbs, returning to the same spot to sleep every night. They leap from tree to tree, letting out joyous whoops as they go, and can jump distances of up to 10 meters.