Background: In Vietnam and many developing countries, private healthcare is increasingly being leveraged by governments to complement public services and increase health service access and utilisation. Extensive understanding of patterns of utilisation of private over public health services, and the rationale for such consumer decisions, is important to ensure and promote safe, affordable and patient-centred care in the two sectors. Few studies within the Southeast Asian Region have explored how private and public providers interact (via social networks, marketing, and direct contact) with consumers to affect their service choices. This study investigates providers’ views on social factors associated with the use of private over public health services in Vietnam. Method: A thematic analysis was undertaken of 30 semi-structured interviews with experienced health system stakeholders from the Vietnam national assembly, government ministries, private health associations, health economic association, as well as public and private hospitals and clinics. Results: Multiple social factors were found to influence the choice of private over public services, including word-of-mouth, the patient-doctor relationship and relationships between healthcare providers, healthcare staff attitudes and behaviour, and marketing. While private providers maximise their use of these social factors, most public providers seem to ignore or show only limited interest in using marketing and other forms of social interaction to improve services to meet patients’ needs, especially those needs beyond strictly medical intervention. However, private providers faced their own particular challenges related to over-advertisement, over-servicing, excessive focus on patients’ demands rather than medical needs, as well as the significant technical requirements for quality and safety. Conclusions: This study has important implications for policy and practice in Vietnam. First, public providers must embrace social interaction with consumers as an effective strategy to improve their service quality. Second, appropriate regulations of private providers are required to protect patients from unnecessary treatments, costs and potential harm. Finally, the insights from this study have direct relevance to many developing countries facing a similar challenge of appropriately managing the growth of the private health sector.