This meta-analytical study examined the effect of neurofeedback on reducing both the (a) inattentive and (b) hyperactive / impulsive components of children diagnosed with Attention- eficit / Hyperactivity Disorder (ADHD). The main finding of the meta-analysis was that theta-beta ratio training achieved identical, statistically significant, and practically large effects on both inattention (g = 0.92) and hyperactivity / impulsivity (g = 0.77). An analysis of the literature indicates that the effectiveness of theta-beta ratio-based neurofeedback appears to derive from a general, top-down effect applicable in the frontal regions of the brain, particularly areas and structures related to information processing. One recommendation emerging from the meta-analysis is for neurofeedback practitioners and researchers to better document details related to site placement and bandwidths in order to identify better protocols based on theta-beta ratios. In addition, the importance of alpha generation was highlighted as a means of going beyond static theta-beta ratios in both the diagnosis of ADHD and the measurement of neurofeedback protocol success over time.