Although researchers have studied disparities in early language development related to socioeconomic status (SES), it is unclear how early and through which mechanisms these differences emerge. As income inequality continues to widen across the world, it is crucial to examine the child-level mechanisms that mediate the effects of SES on individual differences in language development. A deeper understanding of the nature of the differences will allow development of more effective intervention techniques. In this article, we discuss work on child-level cognitive and neural mechanisms underlying the relation between SES and early language development. We discuss possible factors behind individual differences in child-level mechanisms and cascading effects of these differences. We conclude with recommendations for research.