Background: Early care and education providers cite lack of parent engagement as a central barrier to promoting healthy behaviors among young children. However, little research exists about factors influencing parent engagement with promoting healthy eating and activity behaviors in the this setting. Aims: This study aimed to address this gap by examining low and high parent engagement with the "Healthy Me, Healthy We" campaign to identify barriers and facilitators of parent engagement with the intervention. Method: This comparative case study used an explanatory sequential mixed-methods approach. We created center-level parent engagement scores using process evaluation data from the effectiveness trial of "Healthy Me, Healthy We." Recruitment focused on centers with the five lowest and five highest scores. Twenty-eight adults (7 directors, 9 teachers, 12 parents) from seven centers (3 low engagement, 4 high engagement) completed semistructured interviews and the Family and Provider/Teacher Relationship Quality measure. Analytic approaches included descriptive statistical analyses for surveys and a framework-informed thematic analysis for interviews. Results: Prominent contrasts between low- and high-engagement groups involved center culture for parent engagement and health promotion, practices for fostering networks and communication within centers, and communication between centers and parents. Personal attributes of providers (e.g., attitudes) also differentially influenced practices for engaging parents. Discussion and Conclusion: Organizational characteristics and individual practices can facilitate or impede parent engagement with health promotion efforts. Assessing organizational context, gaining input from all stakeholders, and conducting capacity-building interventions may be critical for laying the foundation for positive relationships that support parent engagement in implementation of health promotion programs and beyond.