The present study investigated the extent to which maternal intrusiveness and warmth during play, observed in 579 European American, 412 African American, and 110 more and 131 less acculturated Mexican American low-income families when children were approximately 15 months old, predicted 3 dimensions of the mother–toddler relationship 10 months later. Intrusiveness predicted increases in later child negativity in all 4 groups. Among African Americans only, this association was moderated by maternal warmth. Intrusiveness predicted negative change in child engagement with mothers only in European American families. Finally, near-significant trends suggested that intrusiveness predicted later decreased dyadic mutuality in European American and more acculturated Mexican American families, but not in African American or less acculturated Mexican American families.