In this paper we investigated the real-time processing of epistemic modals in five-year-olds. In a simple reasoning scenario, we monitored children's eye-movements while processing a sentence with modal expressions of different force (might/must). Children were also asked to judge the truth-value of the target sentences at the end of the reasoning task. Consistent with previous findings (Noveck, 2001), we found that children's behavioural responses were much less accurate compared to adults. Their eye-movements, however, revealed that children did not treat the two modal expressions alike. As soon as a modal expression was presented, children and adults showed a similar fixation pattern that varied as a function of the modal expression they heard. It is only at the very end of the sentence that children's fixations diverged from the adult ones. We discuss these findings in relation to the proposal that children narrow down the set of possible outcomes in undetermined reasoning scenarios and endorse only one possibility among several (Acredolo & Horobin, 1987, Ozturk & Papafragou, 2015).