Increasing evidence that positive affect enhances associative processing has lent weight to the idea that positive affect increases false memory for information that is thematically interrelated. Using the Deese–Roediger–McDermott paradigm, we examined whether mild positive affect facilitates monitoring processes in modulating false memory for associate words. When participants in the warned condition – in contrast to those in the unwarned condition – were overtly warned about possible false recognition of the critical lure, we found that positive affect, compared to neutral affect, significantly enhanced monitoring through a warning and reduced false recognition. Signal detection analyses suggest that when a warning is provided, positive affect enhances sensitivity to discriminate list items from critical lures, but it does not shift the overall decision criterion. Taken together, we conclude that positive affect facilitates the effect of a warning in reducing false memories for semantic associates.