Most colobus monkeys exhibit overlap promiscuity. Red colobus monkeys, black colobus monkeys and olive colobus monkeys all live in multimale-multifemale troops with pronounced dominance hierarchies, as expressed by access to food, grooming and mates. The dominant male achieves more than half of the copulations, by far the most of any male.  Mating takes place year-round and the female signifies that she is in estrus by the swelling of the perineum. Both juvenile males and females will mimic this perineal swelling as a means of delaying their expulsion from the natal group.  Overlap promiscuity has evolved in these groups as a result of the fact that no male could defend a food resource that females would be certain to return to, because of the superabundance of food.

Territorial black-and-white colobus monkeys are polygynous, generally living in one-male units with matrilineal female kin groups constituting his harem. This high degree of relatedness between females makes it easier for a male to come into a territory and maintain a harem.  The territory is also defensible because of the way in which the food is distributed; in patches large enough to support the group.  Year-round mating occurs and females give birth approximately ever 2 years.  A male's tenure will only last for about 2 years.
 
 

The red colobus, black colobus and olive colobus maintain patrilineal kin groups, resulting in strong male bonds reinforced by extensive grooming and affection between fathers and male offspring. Females show very little alloparenting, because they are unrelated, and generally tend to most of the juvenile's needs.  For red colobus monkeys, the dominance hierarchy is further reinforced through defense of the troop against chimpanzee predation. The most dominant male leads the charge against oncoming chimpanzees looking to attack. Other members of the group occupy defense roles in proportion to their level within the hierarchy.  Within the larger group, males from small groups with whom they have stronger bonds.  These groups tend to forage together and the members within these small groups groom each other more than they do other members of the troop.

Among territorial black-and-white colobus monkey, female adults display a high degree of alloparenting, because of their genetic similarity.  Females may also defend juveniles collectively from infanticidal males.  The roles of adult males with one another are not well-understood.  Most studies noted instances of more than one adult male living on a territory, yet the nature of these relationships have rarely been explained.  No all-male groups exist and the sex ratio is approximately 1:1 at adulthood, thus more than one adult male would need to live on each territory (Mulhern 1991).

Adult males in red, black and olive colobus groups help handle juvenile males, because of their patrilineal kin groups.  Grooming is the primary activity engaged in by adults and juveniles, which helps reinforce the male-male bonds as the juveniles get older.  In addition, smaller groups of males develop within the larger group, and these smaller groups may include the offspring.  Female adults do most of the nourishing of their offspring and do not let any other females handle their infants.  Females may invest more time in male offspring than female offspring, because greater maternal investment correlates to greater lifetime reproductive success of males, and because fewer males than females reach reproductive age (Struhsaker 1991).  Infanticide has been noted in red colobus monkeys when a new male enters a troop (Starin 1994) as a display of dominance and to induce estrus in females.  The degree of success that this act will correlate with will depend on how well-bonded the female adults are, because they may gang up and attack the male (Starin 1994).

For the black-and-white colobus, only females rear offspring.  Since the females generally are all sisters, all will handle all young.  This act increases the fitness of each one, since many of the genes are similar.  Adult males show no interest in rearing offspring, and primarily defend the territory.  A new male taking over a territory may commit infanticide(Onderdonk 2000).  This act may be risky, however, because of the high degree of relatedness among the female adults. The females will attack an infanticidal or attempted infanticidal male together.