This study examined executive control in sixty-two 5-year-old children who were monolingual or bilingual using behavioral and event-related potentials (ERPs) measures. All children performed equivalently on simple response inhibition (gift delay), but bilingual children outperformed monolinguals on interference suppression and complex response inhibition (go/no-go task). On the go/no-go task, ERPs showed larger P3 amplitudes and shorter N2 and P3 latencies for bilingual children than for monolinguals. These latency and amplitude data were associated with better behavioral performance and better discrimination between stimuli for bilingual children but not for monolingual children. These results clarify the conditions that lead to advantages for bilingual children in executive control and provide the first evidence linking those performance differences to electrophysiological brain differences in children.