This article discusses the processing and acquisition of coreference by monolingual children acquiring Brazilian Portuguese (henceforth BP). More specifically, it is about the development of the coreferential relations established in the scope of the sentence, which are ruled by the principles defined by the Binding Theory. By using a version of the cross-modal picture decision task, we investigated how children acquiring BP process the input, in order to identify the coreferential relations present in the sentences and what role the binding principles play in this process. The results showed that binding principles pose different processing costs, and they also revealed a main effect of age, with adults being faster than children. No main effect of matching was found, but an interaction effect between principle and matching was found. To sum up, the results of this study showed that, as expected, both children, as well as adults, know the binding principles, however, processing them effectively increases with age. The binding principles also pose different processing demands, as reflected in the reaction times shown in our results84718