We examined associations between maternal writing support, math support, and directiveness and children's literacy and math outcomes. Participants were 208 African American, Dominican, Mexican, and Chinese mothers and their first-grade children from low-income households. Mothers were video-recorded playing a grocery game with their children (i.e., making a grocery list together and shopping at a pretend store), and videos were coded for maternal writing and math support and directiveness. Maternal directiveness related negatively to children's literacy and math outcomes, even after controlling for maternal education and ethnicity. Maternal ethnicity did not moderate the relations between maternal directiveness and child outcomes. Maternal writing support did not relate to children's literacy except for a negative association in Chinese families. Maternal math support did not relate to children's math outcomes across ethnicities. Findings can inform intervention programs about family practices that support first graders' academic skills across ethnicities.