Ironic language is challenging for many people to understand, and particularly for children. Comprehending irony is considered a major milestone in children's development, as it requires inferring the intentions of the person who is being ironic. However, the theories of irony comprehension generally do not address developmental changes, and there are limited data on children's processing of verbal irony. In the present pre-registered study, we examined, for the first time, how children process and comprehend written irony in comparison to adults. Seventy participants took part in the study (35 10-year-old children and 35 adults). In the experiment, participants read ironic and literal sentences embedded in story contexts while their eye movements were recorded. They also responded to a text memory question and an inference question after each story, and children's levels of reading skills were measured. Results showed that for both children and adults comprehending written irony was more difficult than for literal texts (the "irony effect") and was more challenging for children than for adults. Moreover, although children showed longer overall reading times than adults, processing of ironic stories was largely similar between children and adults. One group difference was that for children, more accurate irony comprehension was qualified by faster reading times whereas for adults more accurate irony comprehension involved slower reading times. Interestingly, both age groups were able to adapt to task context and improve their irony processing across trials. These results provide new insights about the costs of irony and development of the ability to overcome them.