This study examines how parents' and children's explanatory talk and exploratory behaviors support children's causal reasoning at a museum in San Jose, CA in 2017. One-hundred-nine parent-child dyads (3-6 years; 56 girls, 53 boys; 32 White, 9 Latino/Hispanic, 17 Asian-American, 17 South Asian, 1 Pacific Islander, 26 mixed ethnicity, 7 unreported) played at an air flow exhibit with a nonobvious causal mechanism. Children's causal reasoning was probed afterward. The timing of parents' explanatory talk and exploratory behaviors was related to children's systematic exploration during play. Children's exploratory behavior, and parents' goal setting during play, were related to children's subsequent causal reasoning. These findings support the hypothesis that children's exploration is related to both internal learning processes and external social scaffolding.