A reading disability results from the inability to decode words and may manifest itself as a deficit in reading comprehension. At a neural level, research suggests that a deficiency in the brain process results in the atypical development of word-level and text level. To investigate how the brain processes languages in real-time, researchers use Event-Related potentials (ERPs). The N400 is a delicate ERP waveform that is sensitive to the lexico-semantic aspect of language comprehension. The purpose of this systematic review and meta-analysis is to inquire about the difference in the N400 amplitude between typical and atypical readers to better understand how the brain processes language and comprehension in individuals with RD. Nineteen studies were included in the meta-analysis to explore the standard difference in mean in the N400 amplitude between typical and atypical readers. The analysis showed a Hedge's (g=0.76, p = 0.00). This effect was moderated by the ERP modality, whereby studies that used visual ERP modality were significant with a large (g = 0.82, p< 0.001). Yet studies that used auditory modality had a medium effect size of (g = 0.66, p< 0.001). The anomalous N400 could be due not only to phonological processing deficits.