--- - |2 Abstract Interventions including social scaffolding and metacognitive strategies have been used in educational settings to promote cognition. In addition, increasing evidence shows that computerized process‐based training enhances cognitive skills. However, no prior studies have examined the effect of combining these two training strategies. The goal of this study was to test the combined effect of metacognitive scaffolding and computer‐based training of executive attention in a sample of typically developing preschoolers at the cognitive and brain levels. Compared to children in the regular training protocol and an untrained active control group, children in the metacognitive group showed larger gains on intelligence and significant increases on an electrophysiological index associated with conflict processing. Moreover, changes in the conflict‐related brain activity predicted gains in intelligence in the metacognitive scaffolding group. These results suggest that metacognitive scaffolding boosts the influence of process‐based training on cognitive efficiency and brain plasticity related to executive attention. - Developmental Science, EarlyView.