Patient and citizen engagement is taking root in a number of healthcare organizations. These initiatives show promising results but require a supportive environment to bring systemic and sustainable impacts. In this synthesis article, we propose an ecosystemic perspective on engagement in health, outlining key elements at the individual, organizational and systemic levels supporting reciprocal and effective relationships among all partners to provide conditions for the co-production of health and care. We argue that growing a healthy engagement ecosystem requires: (1) building local and national "hubs" to facilitate learning and capacity building across engagement domains, populations and contexts; (2) supporting reciprocal partnerships based on co-leadership; and (3) strengthening capacities for research, evaluation and co-training of all partners to support reflective engagement practices that bring about effective change. An Ecosystemic, Reciprocal Perspective on Patient and Citizen Engagement Relationships Ecosystems are communities of individuals interacting with their environment (Gurevitch et al. 2002: 522). Ecosystems are "holonic structures": they are made of entities that are a whole and a part of a larger system at the same time (e.g., atoms, cells, organisms, planet), with the levels dynamically interacting with one another (Koestler 1967: 48). In healthcare, individuals are embedded within the healthcare organizations and systems they interact with (Mella and Gazzola 2017). An ecosystemic perspective on patient and citizen engagement reminds us that healthcare, in its essence, is about relationships between people. This perspective also highlights the idea that these relationships