They are primarily folivores but also significant frugivores, acting as seed dispersal agents through their digestive system and their locomotion.

Threats include human predation, habitat destruction, illegal wildlife trade, and capture for pets or zoo animals.

Fully grown adult howler monkeys do not often rely on their tails for full-body support, but juveniles do so more frequently.

Mantled howler monkeys are an exception, commonly living in groups of 15 to 20 individuals with more than three adult males.

Physical fighting among group members is infrequent and generally of short duration, but serious injuries can result.

[9][10] Group size varies by species and by location, with an approximate ratio of one male to four females.

[11] The function of howling is thought to relate to intergroup spacing and territory protection, as well as possibly to mate-guarding.

Black howler monkeys incorporate information on resource availability along with neighbors’ current location.

Howlers eat mainly top canopy leaves, together with fruit, buds, flowers, and nuts.

[13] Howler monkeys are also known to occasionally raid birds' nests, chicken coops, and consume the eggs.

In larger groups and increased rainfall, frugivory decreases as a result of competition and fast food depletion.

John Lloyd Stephens described the howler monkeys at the Maya ruins of Copán as "grave and solemn, almost emotionally wounded, as if officiating as the guardians of consecrated ground".

Two howler monkey brothers play a role in the myth of the Maya Hero Twins included in the Popol Vuh, a widely feared tale of soul and passion.