This special issue of Health Systems & Reform on Networks of Care helps us understand the water in which we are swimming. First, it presents a definition of a Network of Care: "a group of public and/or private sector service delivery sites deliberately interconnected through an administrative and clinical management model which promotes a structure and culture that prioritizes client-centered, effective, efficient operation and collaborative learning, enabling providers across all levels of care, not excluding the community, to work in teams and share responsibility for outcomes." Defined thus, this concept offers the promise of a pragmatic approach to managing service delivery that can be applied throughout a health system, identifying ways for multiple sites to work together, adapt to new challenges, better ensure integration of care, and promote the more effective use of resources throughout. The subsequent papers in the series offer a practical evidence-based vision-based on lessons from experts, literature reviews, and direct case study observations-that can lead us from knowledge to action in building transformative Networks of Care in diverse settings around the world.