Plasticity may be enhanced in the developing brain, but mechanisms are poorly understood. Transcranial magnetic stimulation (TMS) offers increasingly sophisticated means of assessing neurophysiology and mechanisms of neuroplasticity in vivo in adults. Paired associative stimulation (PAS) is an advanced modality that pairs sensory electrical peripheral nerve stimulation with TMS over the contralateral motor strip (M1). PAS induces rapidly evolving, long lasting, reversible and topographically specific increases in M1 excitability in adults consistent with NMDAR-dependent long-term potentiation (LTP). PAS has not been studied in the more plastic brains of children. Our aim was to determine the developmental profile of PAS neurophysiology in school-aged children, evaluating the putative correlation of PAS effect with age, and possible endogenous systems that may be modulators of PAS (i.e. Shot-Interval Intracortical Inhibition) and dictating plasticity. Twenty-eight children aged 6-18 years underwent PAS evaluations. Eighteen had significant PAS responses that were reproducible on repeat testing. Addition of inhibitory paired-pulse TMS appeared to block the PAS effect. The PAS effect did not correlate with age. PAS is safe and tolerable with effects comparable to adults. PAS may carry clinical and research utility in perinatal stroke and other pediatric brain injury populations.