The growing burden of non-communicable and newly emerging communicable diseases, multi-morbidity, increasing health inequalities, the health effects of climate change and natural disasters and the revolution in communication technology require a shift of focus towards more preventive, people-centred and community-based health services. This has implications for the health workforce, which needs to develop new capacities and skills, many of which are at the core of health promotion. Health promotion is thus being mainstreamed into modern public health. For health promotion, this offers both opportunities and challenges. A stronger focus on the enablers of health enhances the strategic importance of health promotion's whole-of-society approach to health, showcases the achievements of health promotion with regard to core professional competencies, and helps build public health capacity with health promotion accents. On the other hand, mainstreaming health promotion can weaken its organizational capacity and visibility, and bears the risk of it being absorbed into a traditional public health discourse dominated by medical professions. To address these challenges and grasp the opportunities, it is essential for the health promotion workforce to position itself within the diversifying primary care and public health field. Taking the transdisciplinary status of health promotion and existing capacity development systems in primary and secondary prevention and health promotion as reference points, this paper considers the possibilities to integrate and implement health promotion capacities within and across disciplinary boundaries, arguing that the contribution of health promotion to public health development lies in the complementary nature of specialist and mainstreamed health promotion.