Evidentials are grammatical source-of-knowledge markers. In Bulgarian they provide information about authorship – whether the speaker has personally acquired the information or not – and modality – whether perceptual or cognitive mechanisms were involved in the information's generation. In two experiments, Bulgarian kindergarteners and third-graders (ages 6 and 9, N=96) had to decide which one of two utterances containing different evidentials to believe. Experiment 1 showed that children draw on modality information in their decisions: Third-graders favored perceptual over cognitive and kindergartners cognitive over perceptual sources. Experiment 2 showed that third-graders can also draw on the authorship information carried by evidentials: they favored first- over second-hand information. The discussion focuses on understanding the development of children's use of evidentials.