Negative emotionality and effortful control consistently predict child adjustment, yet few studies explore their interactive effects on adjustment. In concurrent and longitudinal (one-year follow-up) analyses, we examined negative emotionality-by-effortful control interactions in predicting anxiety, depression, and conduct problems in 214 children aged 8-12. Temperament was assessed using behavioral tasks measuring fear, frustration, executive control, and delay ability. An interaction between frustration and executive control predicting conduct problems was observed; higher executive control was related to fewer concurrent conduct problems for those moderate to high in frustration, but did not predict conduct problems for those low in frustration. This interaction did not predict conduct problems one year later. No support was found for negative emotionality-by-effortful control interactions predicting anxiety or depression. Our findings highlight the importance of executive control during preadolescence and provide mixed evidence regarding whether facets of negative emotionality and executive control interact with one another to influence adjustment.