Research Findings: Greater self-regulation has been identified as a protective factor for low-income children's academic achievement. However, we know less about the long-term protective nature of specific aspects of self-regulation. Data were drawn from predominantly African American and Latino children in low-income communities in Boston, Chicago, and San Antonio during early childhood (mean age = 4.84 years) and middle childhood (mean age = 9.30 years; n = 348). The current investigation found that preschoolers' overall self-regulation predicted their academic skills in middle childhood, net of child and family characteristics as well as academic competence during preschool. Furthermore, when executive function (EF) and effortful control (EC) in early childhood were examined as simultaneous predictors of quantitative and literacy scores during middle childhood, there were moderate linkages from EF to both academic domains. Practice or Policy: Our findings suggest that the long-term gains of interventions that focus on fostering global self-regulation in preschool may yield more benefits for math than for reading, especially if such programs target young children's executive function in particular.