In common with other night monkeys, the gray-handed night monkey is one of the few monogamous monkeys.[1] The monogamous pair generally gives birth to a single infant each year, although twins occasionally occur.[2] The gestation period is about 133 days.[4] The father carries the infant from the time it is one or two days old, passing it to the mother for nursing.[2] Average interbirth interval for the mother is 271 days.[4]