Display omitted •Work engagement increases emotional exhaustion for some individuals but not others.•Conscientious people are better able to stay engaged at work without being exhausted.•Unstable workers who are not conscientious face difficulties when engaged at work.•For some people, engagement results in exhaustion and subsequent deviant behavior.•Work engagement has similar positive and negative implications in the U.S. and China. How might work engagement help predict emotional exhaustion? Incorporating the notion that work engagement and emotional exhaustion represent two ends of a continuum, we drew on the conservation of resources (COR) theory—which examines them as two distinct constructs—to conduct a multicontext, two-study investigation in the U.S. and China. We proposed that work engagement would increase emotional exhaustion for individuals who rated lower in the conscientiousness personality trait. Furthermore, we found a three-way interaction, whereby work engagement increased emotional exhaustion for less conscientious individuals who were also neurotic or emotionally unstable, while conversely decreasing emotional exhaustion for more conscientious individuals who are emotionally stable. Our results also support a moderated-mediation model, revealing that work engagement decreased counterproductive work behavior as a result of reduced emotional exhaustion when both conscientiousness and emotional stability were high. Implications for future work engagement and counterproductive work behavior research are offered.