The New York City Health and Hospitals Corporation (HHC) is a mission-driven, $54 billion, public benefit corporation serving 13 million New York City residents-the largest municipal hospital and health care system int the United States. In response to external pressures, HHC has undertaken a series of improvement initiatives that appear to be transforming its organizational culture, systems, and care processes. This case study describes how HHC is achieving higher levels of performance through a common clinical information system that promotes information continuity across care settings, care coordination to improve chronic disease management, teamwork and continuous innovation to improve the quality and value of care, and access to appropriate care that is responsive to patients needs. Factors that the organizations leaders identify as critical to successful change include strategic use of information technology, leadership to promote collaborative learning and staff initiative, spread of best practices, alignment of financial incentives, and transparency of results