Research Findings: Interpersonal relationships among staff caregivers, parents, and children have been recommended as essential aspects of early childhood intervention. This study explored the associations of these relationships with program outcomes for children and parents in 3 Early Head Start programs. A total of 71 children (8-35 months, M=20), their parents, and 33 program caregivers participated. The results showed that caregiver-child relationships were moderately positive, secure, and interactive and improved in quality over 6 months, whereas caregiver-parent relationships were generally positive and temporally stable. Caregiver-child relationships were more positive for girls, younger children, and those in home-visiting programs. Caregiver-parent relationships were more positive when parents had higher education levels and when staff had more years of experience, had more positive work environments, or had attained a Child Development Associate credential or associate's level of education rather than a 4-year academic degree. Hierarchical linear modeling analysis suggested that the quality of the caregiver-parent relationship was a stronger predictor of both child and parent outcomes than was the quality of the caregiver-child relationship. There were also moderation effects: Stronger associations of caregiver-parent relationships with observed positive parenting were seen in parents with lower education levels and when program caregivers had higher levels of education. Practice or Policy: The results support the importance of caregiver-family relationships in early intervention programs and suggest that staff need to be prepared to build relationships with children and families in individualized ways. Limitations of this study and implications for program improvements and future research are discussed. (author abstract)