Lions are the world's most social felines. They live in groups of related females, called prides, which may comprise several to as many as 40 individuals, including adults, sub-adults (between the ages of 2 and 4) and cubs, plus one or more resident males. Abundance of prey availability plays a significant role in the size of a lion pride. Pride mates associate in sub-groups within the pride.

Females usually stay in their mothers' prides for life, unless food scarcity forces them out. Young males are driven from their prides when they grow large enough to compete with the dominant males (usually between the ages of 2 and 4). They create coalitions, usually with brothers and cousins, and search for a pride to take over. Males entering a new pride will kill all cubs that cannot run from them. Adult males that are fortunate enough to achieve residency within a pride hold tenure for an average of two years, often leaving due to eviction by another coalition of males. In India, female and male lions live apart, joining only to mate.

Males take on most of the defensive duties. However, both males and females mark their territories by roaring — which can be heard up to five miles away — and scent marking with urine. Females raise the cubs and are the primary hunters, although males will sometimes join females during a hunt. Depending on the prey item, several lions may stalk prey from different angles to within 100 feet (30 meters) before attacking the targeted animal. Nomadic males must hunt alone or scavenge from other animals.