Since 2002, it has become clear that a broader, inclusive State Public Health (SPH) Laboratory System is more effective in ensuring that the core functions are fulfilled. Within the last decade, work has been done in measuring the laboratory infrastructure in support of the essential public health services, creating performance standards for public health entities, identifying public health workforce needs, and addressing quality systems as they apply to public health laboratory services. As we move into the 21st century, these 11 core functions of SPH Laboratories remain unchanged. However, what has emerged is the realization that laboratory services in support of public health are dependent upon synergistic and effective interactions among many different partners at the State and national level. This revision of the Core Functions of SPH Laboratories more clearly defines the responsibilities of the SPH Laboratory within the SPH Laboratory System.