We studied mother-infant relationships and infant independence in wild Geoffroy's spider monkeys (Ateles geoffroyi) during the first 3 years of infant life. We used 15-min focal sampling to collect data on mother-infant interactions and infant behavior in 12 mother-infant dyads in the Yucatan peninsula, Mexico. Data were analyzed using generalized linear mixed models. Newborns spent almost all their time in proximity and in contact with their mothers. The time infants spent within one-arm reach from the mother decreased with age, and the infant was primarily responsible for maintaining proximity. The time infants spent farther than 8 m from the mother, in independent locomotion, exploration, and proximity with group members other than the mother increased with age. We identified two developmental periods associated with critical milestones of infant independence: the first at 8 to 10 months when independent locomotion and exploration began, and the proportion of time in proximity with group members other than the mother increased and the second at 19 to 21 months when the mother's rejection started, maternal carrying ended and mother's help, in the form of bridging canopy gaps, peaked. Compared with other primate species of similar size, Ateles geoffroyi have an extended dependence period, which could be related to the cognitive and developmental challenges imposed by their socioecological characteristics. (PsycInfo Database Record (c) 2022 APA, all rights reserved).