This chapter focuses on the phenomenon of bilingualism having positive collateral effects on general-domain executive control. It provides a broad introduction to what causes bilingualism to affect general-domain executive control. The chapter briefly reviews the first experimental studies with children, which started settling the guidelines of the empirical research on the issue. It discusses findings on the effect that bilingualism has on one executive control process in particular: conflict processing. Specifically, there are two different components relevant for conflict processing and, hence, to deal with the sort of experimental task: conflict resolution and conflict monitoring. The chapter also reviews evidence that being a bilingual entails the development of more efficient executive control across lifespan. The impact of bilingualism on conflict resolution seems to reflect a better functioning of inhibitory control mechanisms in bilingual compared to monolingual speakers. Finally, the chapter highlights the critical issues for future research.