Sharing food with immature individuals is costly and should therefore only occur when the benefits outweigh the costs. Accordingly, sharing typically decreases when immature individuals get older and become more proficient independent foragers. Providers would gain more if they could adjust food sharing not only to immature age but also to their skill level. Such sensitivity to others' skill deficits is expected to be rare, but may be found in species with high prosociality and other-regarding preferences, such as cooperative breeders. Here, we compared the food-sharing patterns of cooperatively breeding common marmosets (