The pervasive income-related achievement gap among children has been partially explained by parental investments. Wealthier parents provide more cognitively enriched environments (e.g., books, informal learning opportunities such as music lessons) and converse more with their children relative to low-income parents. However parental investment only partially accounts for the income-achievement gap. On average, low-income children have more difficulty regulating their emotions and behavior in comparison to their wealthier counterparts. Academic achievement is a function not only of cognitive competencies but also encompasses emotional and behavioral components that could also contribute to the income-achievement gap. In Study 1, family income among rural, White 9-year-olds is positively related to delay of gratification skill. This, in turn, accounts for subsequent, middle school grades at age 13. In Study 2, family income during early childhood (age 2 to Grade 3) in an ethnically diverse, national sample predicts cognitive development in 5th graders, controlling for prior levels of cognitive development at 15 months. This prospective, longitudinal relation is again mediated by delay of gratification skills. Evidence is also presented in Study 2 that the income [right arrow] self-regulation [right arrow] achievement path operates independently of parental investment. Analyses of both sets of data also include multiple indices of familial characteristics (e.g., maternal education, ethnicity, single-parent status). Early childhood poverty matters for later academic achievement but reasons encompass both cognitive and socioemotional processes. (Contains 5 tables.)