As effortful control (EC), the self-regulation aspect of temperament, has been argued to play a key role in the normal and psychopathological course of development, research adding to the construct validity of EC is needed. In the current study, interrelations between the temperament construct of EC and the efficiency of the executive attention network, argued to underlie EC, were investigated, using event-related potentials (ERPs). In general, children scoring low on EC questionnaires made more errors of commission in the Go/No-Go task and showed smaller No-Go N2 or No-Go P3 amplitudes, two ERP components related to the executive attention network. The two EC scales (Effortful Control Scale and Attentional Control Scale), used in the current study, were differentially related to the outcome, indicating that they may measure different constructs. No-Go P3 amplitude was noted to be associated more strongly with EC than No-Go N2 amplitude. EC was found to be implicated in Attention-Deficit Hyperactivity Disorder (ADHD) symptomatology, as children scoring high on ADHD symptoms scored low on EC questionnaires, made more errors of commission, and showed smaller No-Go P3 amplitudes.