Attention-Deficit/Hyperactivity Disorder (ADHD) is a highly prevalent disorder, incurring billions of dollars of costs annually, for which there is a rel need for additional non-pharmacologic treatments. Deficits in maintaining attentional control manifest as inconsistent intra-individual performance on sustained attention tasks with periods of normal performance and other periods of poor performance thought to reflect inattention, and is considered by several groups to be an important component of ADHD. Research by our team members on the behavioral and neurophysiological bases of sustaining attentional control reveal infra-slow fluctuations in performance and in brain signals related to sustained attention to targets, suppression of distractors and mind wandering. We have created an innovative (patent pending) product that directly targets these three components of sustained attentional control in ADHD. The Sustained Attentional Control (SAC) training utilizes the ubiquity of mobile-apps to train adults with ADHD in all contexts of real life. Our approach combines building attentional control skills with awareness of attentional control and includes active transfer of the experiential sense of three attentional control components to real life activities (sustained focus, suppression of distractions and mind wandering). This Phase-I project is aimed at demonstrating the efficacy of the SAC product for training sustained attentional control in adults with ADHD. In Aim-1 we build on the existing code framework of our current apps and the back-end data system, to complete the programming and artwork for the remaining set of training apps and optimize them for adults with ADHD. In Aim-2 we test the efficacy of SAC training - 100 subjects will be randomly assigned to either a Treatment Condition (SAC training), or Control Condition with equivalent app usage and contact, but without factors hypothesized to provide training benefits. We will determine the amount of improvement between Pre- and Post- Training in each condition and compare these improvements between Treatment and Control conditions using behavioral and neurophysiological outcome measures.