There are mainly three Credentialing Organizations and they are:
American Nurses Association/American Nurses Credentialing Center: The American Nurses Association (ANA) defines certification as "a means of measuring competency, and the identification of competent nurses that will promote the public welfare for quality in health care." The ANA's credentialing arm, the American Nurses Credentialing Center (ANCC), is the largest nurse credentialing organization in the United States. More than a quarter million nurses have been certified by ANCC since 1991.

American Association of Critical Care Nurses: The American Association of Critical Care Nurses (AACN) offers its own credentialing program specifically for critical care nurses. Like the ANA/ANCC, an AACN credential requires a qualifying examination and has its own set of requirements which RNs must meet in order to take the credentialing examination. Critical care nurses without baccalaureate degrees in nursing are eligible to earn the certification for adult, neonatal, and pediatric critical care nurses (CCRN). The AACN also offers a clinical specialist credential (CCNS) for master's prepared RNs and national acute care nurse practitioners (ACNPs).

Other professional nursing associations in specialty practice areas: Several professional nursing associations representing specialty areas have their own credentialing programs. Some compete with the credentials offered by the ANA/ANCC. Others provide credentials for nurses in specialties for which the ANA/ANCC does not have an equivalent.