Children's classroom engagement during the first years of formal schooling is foundational to their academic success. Previous research has found that the quality of communication between parents and teachers as well as child and family characteristics are associated with children's engagement scores in the classroom. However, research remains limited, and most has been conducted among middle and high school students. Even less is known about the role of communication quality between parents and teachers on children's classroom engagement during preschool, when children are encountering the formal education system for the first time and the foundation for their school trajectories are being laid. This study explores the association between parent-teacher communication quality and child and family characteristics on the classroom engagement scores of 326 low-income, ethnoracially and linguistically diverse children attending Head Start, using a teacher and observer-rated measure of child engagement. Results showed that when teachers perceived having a high-quality communication with the child's parent, the child was rated to be more engaged in the classroom by both their teachers and independent observers. However, parent and child characteristics (i.e., parent race/ethnicity, children's English language skills, child gender, and child age) were only significantly associated with children's classroom engagement when rated by their teachers but not by independent observers. These findings suggest that building relationships with families early on might be a promising way that schools can support the wellbeing of minoritized children. (author abstract)