Transcranial direct-current stimulation (tDCS) is a form of non-invasive brain stimulation applied in both healthy and clinical populations. Application of weak current induces electric fields at the neuronal level, and may lead to behavioral effects such as enhanced motor learning when paired with training. Nearly all investigations to date have been completed in the adult brain, and fundamental studies are lacking in pediatrics, yet are required to advance and optimize tDCS application in this population. Additionally, given the ability of tDCS to enhance motor learning, translation to complex motor skill acquisition is necessary to define the full potential of tDCS. Here we investigated the effects of tDCS on motor learning in healthy children, with subsequent probing of neurophysiological changes underlying these behavioral changes using transcranial magnetic stimulation. Next, we compared tDCS-induced electric fields in the child, adolescent, and adult brain, using computational current modeling. Given the therapeutic potential of tDCS in pediatrics, we examined the safety and feasibility of tDCS application in childhood stroke. Finally, we examined the effects of tDCS on complex motor skill acquisition, including laparoscopic surgical and neurosurgical skills in medical trainees. Our findings suggest that tDCS can safely enhance motor learning in healthy children and young adults. Neurophysiological mechanisms underlying these changes appear to be variable. Current modeling suggests that children are exposed to substantially stronger electric fields compared to adults, possibly contributing to the complex neurophysiological changes seen with tDCS application in children. Despite inducing stronger electric fields, application of tDCS appears to be safe in children and adolescents. tDCS-enhanced motor learning may not be restricted to basic motor skills, but complex laparoscopic surgical skills, and neurosurgical tumor resection skills may be sensitive to enhancement as well. In summary, our findings suggest that tDCS application is safe in the developing brain, and capable of producing robust behavioral changes. These findings support the translation of tDCS to pediatric therapeutic investigations. Neurophysiological mechanisms of these changes require further investigation. Establishing the ability of tDCS to enhance surgical skill acquisition may counteract the current short-comings of surgical training, revolutionizing the field of medical education.