Childhood socioeconomic status (SES) predicts many important life outcomes, from physical and mental health to academic achievement and cognitive ability. Why is SES so influential? Part of the answer lies in the relationship between SES and the brain. I will present research from my lab and others aimed at characterizing SES differences in brain structure and function. I will then discuss the causes of these associations – by what mechanisms are they linked? – and their consequences – what roles do they play in the health and achievement disparities mentioned earlier? Finally, I will consider whether and how the neuroscience of SES can help shape policies concerning children of low SES.