A burgeoning literature has recently begun investigating the links between socioeconomic inequality and the developing brain. This work suggests widespread disparities in both brain structure and function that begin as early as the first year of life. Here we review disparities in neural structure that have been reported in both cortical and subcortical gray matter, as well as in white matter. Disparities in brain function have also been reported, particularly in circuits that support language, memory, executive functioning, and emotion processing. We additionally review recent work investigating the mechanisms that underlie socioeconomic disparities in brain development. Taken together, this work has the potential to identify important targets for intervention in policy and practice.