Multistakeholder regional collaboratives have assumed a prominent role in producing public reports about health care providers' performance. I conducted an in-depth study of eight such US collaboratives, examining their accomplishments, management practices, and future challenges. I found that these collaboratives have made key contributions to public reporting and have built trust and cooperation among stakeholders who, in other settings, are competitive or even adversarial. Challenges for collaboratives include securing ongoing funding; negotiating complex and contentious issues around expanded reporting activities, such as publishing measures of providers' efficiency; and establishing more flexible and efficient decision-making processes.