To investigate how parents support children's learning at an exhibit on evolution, the conversations of 12 families were recorded, transcribed, and coded (6,263 utterances). Children (mean age 9.6 years) and parents visited Explore Evolution, which conveyed current research about the evolution of seven organisms. Families were engaged with the exhibit, staying an average of 44 minutes. Parents' and children's explanatory, nonexplanatory, and evolutionary conversation was coded. Overall, substantive explanatory conversation occurred in 65% of parent utterances, whereas nonexplanatory conversation occurred in 21% of the utterances. We found substantial use of exhibit text by parents (12.9% of utterances) who read it aloud and reframed the text for their children. Parents also used evolutionary terms and evolutionary concepts (10.2%), showing that such an exhibit is a valuable way to introduce this difficult topic to elementary-school-aged children. Parents' use of explanatory conversation positively related to their children's use of explanatory and evolutionary conversation, indicating that a dialogic interchange was occurring. Parents' attitudes toward the exhibit content, particularly the issue of human evolution, related to the museum experience. Overall, this analysis shows that parents and children are having nuanced discussions and illustrates the potential of informal experiences in supporting children's learning of a complex topic. (Contains 4 tables, 2 figures, and 1 footnote.)