The present study investigates how peer presence influences children’s free-play behavior. We tested children (ages 2 to 11) from two different cultural environments: the lowlands of Bolivia (Experiment 1), and the United States (Experiment 2). We presented children with toys hidden in envelopes to explore either with a familiar peer or without. Bolivian Tsimane’ children discovered significantly more objects with a peer, over and above the effect that would be expected from simply having two children search the toys independently in parallel. Additionally, Tsimane’ children discovered more objects as a function of age. Peer presence facilitated exploration in younger United States children but inhibited exploration in older United States children, relative to exploration rate without the peer. Taken together, peer presence facilitates exploration among young children across both cultures. The positive effect of peer presence on discovery rate may be driven by an increase in competition for resource control.