The Multistate Learning Collaborative on Performance and Capacity Assessment or Accreditation of Public Health Departments (MLC) is an initiative undertaken with the Exploring Accreditation Project (EAP). The EAP is jointly funded by the Robert Wood Johnson Foundation (RWJF) and the Centers for Disease Control and Prevention (CDC), and staffed collaboratively by the Association of State and Territorial Health Officials (ASTHO) and the National Association of County and City Health Officials (NACCHO) to explore the implications and feasibility of a national public health accreditation system. The MLC, also financially supported through grants from RWJF, is designed under the auspices of the National Network of Public Health Institutes (NNPHI) and the Public Health Leadership Society (PHLS) to enhance the accreditation/assessment activities already underway in each of the grantee states; to promote learning among the states participating in the collaborative; to disseminate information to state and local health departments nationally; and to inform the work of the EAP. Five states with mature accreditation or assessment programs were selected from among 18 applicants. This article describes the ongoing work, including breakthroughs and challenges, in these natural laboratories so that this information may be a resource for other states as well as nationally.