Emerging natural and man-made threats to the health of the nations population require development of a seamless laboratory network to address preventable health risks; this can be achieved only by defining the role of public health laboratories in public and private laboratory service delivery. Establishing defined core functions and capabilities for state public health laboratories will provide a basis for assessing and improving quality laboratory activities. Defining public health laboratory functions in support of public health programs is the beginning of the process of developing performance standards for laboratories, against which state public health laboratories, and eventually local public health and clinical laboratories, will establish and implement best laboratory practices. Public health is changing, and as apart of that change, public health laboratories must advocate for and implement improvements for public health testing and surveillance. These changes are outlined also in the Association of Public Health Laboratories consensus report (Association of Public Health Laboratories. Core functions and capabilities of state public health laboratories: a white paper for use in understanding the role and value of public health laboratories in protecting our nation's health. Washington, DC: Association of Public Health Laboratories, 2000).