Children are exposed to a range of unrealistic fiction, which they recognize as unrealistic. But it remains unknown whether children understand the distinction between different genres of unrealistic fiction, specifically science fiction and fantasy. We asked whether children have consistent expectations about the events that tend to occur in these two types of stories and whether children expect these stories to have a consistent genre over the course of their narratives. To do so, we read 4- to 6-year-old children (N = 90) a story from 1 of 3 different fictional genres: realistic, science fiction, or fantasy. We then asked children to choose between a matching ending from the same genre and an ending from one of the other genres. Children successfully chose the matching ending for the science fiction and fantasy story genres when the matching ending was pitted against the other unrealistic ending, suggesting that children are sensitive to the distinction between these two unrealistic fictional genres. However, children tended to choose the realistic ending when asked to choose between this ending and a matching unrealistic ending, replicating previous work that children have a bias toward reality when completing stories.