In social insect colonies, individuals need to communicate to coordinate cooperative tasks and protect the colony and its resources against intruders. To maintain colony integrity, it can be particularly important to recognize nestmates and discriminate against non-nestmate conspecifics and heterospecific predators and parasites. As typical intruders are either con- or heterospecific adults, the mechanisms underlying recognition and discrimination processes in interactions among adults have been well described. Ant brood (eggs, larvae, and pupae) can also play a key role in social interactions, and brood is of special importance when it comes to the priorities of worker ants. However, whether ants can, or even need to, recognize brood of different origins, is not always clear. In this review, we integrate the results of 100 years of study on brood recognition and discrimination in ants into a general framework. We begin with an overview of the proximate mechanisms involved in brood recognition and discrimination. We then discuss why brood recognition and discrimination should evolve and review the evidence for brood recognition on three organizational levels: within nests, between conspecifics and between species. We conclude by examining the constraints acting on accurate recognition and/or discrimination. With this review, we hope to inspire future research on the fascinating life of ant brood.