​​In 2009, the Centers for Disease Control and Prevention, in partnership with the Association of Schools of Public Health and the University of Washington's Center for Public Health Informatics, convened a Working Group to Define Competencies for Public Health Informaticians. This working group developed a formal definition for a public health informatician and a unique set of competencies for professionals working in the field of public health informatics. Created within the context of the Core Competencies for Public Health Professionals (Core Competencies), the Competencies for Public Health Informaticians were designed as an additional domain to supplement the eight domains within the Core Competencies. The Competencies for Public Health Informaticians are organized into two tiers, which reflect competencies for public health informaticians and senior public health informaticians.