OBJECTIVES: In most primate species that live in social groups, non-mothers frequently interact with infants leading to significant impacts on maternal care strategies and both infant socialization and survivorship. In this study, we focused on infant handling by non-mother individuals in mantled howler monkeys (Alouatta palliata), a species for which very little information is available on this topic. MATERIALS AND METHODS: Using focal-animal sampling for 743 h, we observed 218 instances of interest and 232 handling events involving 14 infants (i.e., 1 to 12 months of age) living in four groups in southern Mexico. RESULTS: Interest and handling occurred at similar rates, 0.3 events per hour. Most handling was positive, involving behaviors such as making contact and friendly touching, whereas aggressive behaviors, such as harassing and kidnapping, were infrequent. Adult females, especially when lactating, were the primary handlers, contrasting with findings in other primate species where juveniles or non-lactating females are usually more involved. Handling began within the first week of life and was most frequent during the first 3 months. Mothers rarely intervened in handling, doing so primarily during infrequent kidnapping events. DISCUSSION: These findings contribute to our understanding of primate social behavior, particularly in species with low social activity levels, and provide a basis for future research on the implications of infant handling for group dynamics and infant development.