Allomothering, allomaternal infant care/handling, or non-maternal infant care/handling is performed by any group member other than the mother. Alloparental care is provided by group members other than the genetic father or the mother and thus is distinguished from parental care. Both are widespread phenomena among social insects, birds and mammals.

Allomothering comprises a wide variety of behaviors including: carrying, provisioning, grooming, touching, nursing (allonursing), and protecting infants from predators or conspecifics. Depending on age-sex composition of groups, alloparents, helpers or "handlers" can be non-reproductive males in polyandrous systems, reproductive or non-reproductive adult females, young or older juveniles, or older brothers or sisters helping to raise their younger siblings.

The term allomother first appeared in a sociobiological analysis of reproductive strategies among langur monkeys and referred to group members other than the mother who share care of infants. Allomothering turns out to be common across the primate order and occurs in vervets, cebus monkeys, squirrel monkeys, various macaques, New World monkeys and prosimians as female or male group members assist the mother by carrying or guarding infants from predators, and in some New World monkeys such as tamarins and marmosets, helping to provision them.

Allomaternal care varies greatly across and within different species, families, subfamilies, and groups of primates. Mothers within the same group often vary significantly in the amount of access they allow allomothers. Differing levels of allomaternal care are present in almost 75% of primate species for which there is data and among 100% of callitrichids. Allomaternal care by adult males is most often provided in species in which there is a relatively high degree of paternity certainty, such as within pair living species. However, unrelated adult males have been observed to provide allomaternal care as in fat-tailed dwarf lemurs and Barbary macaques.

The majority of allomaternal care in group living primate species is provided by females and juveniles. Juveniles are often older siblings, but do not necessarily provide allomaternal care exclusively to their siblings. Allomothering is most common in species with close female relationships and relaxed female dominance hierarchies.

The number of allomothers involved in the allomaternal care of a single infant varies by species. In hanuman langurs, infants receive allomaternal care from most of the females within the group, while in capped langurs, one adult female typically acts as the primary allomother for an infant.

The age at which infants receive care from allomothers also varies greatly by species. Research on wedge-capped capuchins has found that infants receive no allomaternal care during the first three months of their lives, and they receive the greatest amounts of allomaternal care between the ages of four and six months. However, potential allomothers show interest and investigate infants who are under three months old. Alternatively, research on wild capped langurs found that infants spent about one-third of their time with a single allomother during their first month of life, and after this point, time engaged in allomaternal care declined. Wild Formosan macaque infants receive the highest rates of allomaternal handling between the ages of four and seven weeks, and allomaternal care rates decrease greatly between 20 and 24 weeks of age.

There is evidence that some primate species differentially provide allomaternal care based on the infant's sex. This sex-bias in allomaternal care is noted in wild Formosan macaques. In a study of this species, adult females participated in higher rates of allomaternal care with female infants than with male infants, while juvenile females engaged in higher rates of allomaternal care with male infants than with female infants.