Nursing candidates must prepare by a rigorous course of training that includes a thorough grounding in anatomy, physiology, pharmacology, the cause and treatment of disease, the intricacies of nutrition and diet, surgical skills, and a variety of techniques pertaining to patient care. Many nurses also prepare for more specialized work, such as the care of newborn infants, maternity patients, or the mentally ill, or for duties in the operating room.

Training for a career as a registered nurse (RN) can be met by several means: a two-year course at a junior college or a four-year degree program at a college or university. (Three-year courses given by hospitals are being phased out because of high costs.) Emphasis on college education for nurses is on the upsurge, because greater knowledge is required to apply the latest methods of diagnosis and therapy. Training includes both classroom study and actual hospital practice, and the graduate must still be examined and licensed by the state. This applies also to women in religious orders who train and work as nursing sisters.

The age limits and educational requirements for practical nurses are less stringent, and the period of training is much shorter, usually one year. The terms licensed practical nurse (LPN) and licensed vocational nurse (LVN) are interchangeable. Sufficient training is given to such men and women to enable them to care for and feed patients, administer medication, and perform other routine duties; however, they are always under the direct supervision of registered nurses. LPNs are generally examined and licensed by the state.

For most specialized work and teaching, nurses must complete a course leading to a master's degree or doctorate. Specializations include nurse anesthetist, which originated at the beginning of the 20th cent., and such recently established ones as nurse practitioner (licensed to perform physical examinations and other procedures under a physician's supervision), nurse midwife (see midwifery), and nurse clinician. In addition to duties in the hospital or in the home there are many fields open to the professional nurse, such as the Red Cross, military service, public health, health insurance companies, industry, and teaching. Some nurse practitioners have become primary health-care providers, opening practices on their own (without physician supervision), and some have been accredited as such by large health maintenance organizations.

In ancient times, when medical lore was associated with good or evil spirits, the sick were usually cared for in temples and houses of worship. In the early Christian era nursing duties were undertaken by certain women in the church, their services being extended to patients in their homes. These women had no real training by today's standards, but experience taught them valuable skills, especially in the use of herbs and drugs, and some gained fame as the physicians of their era. In later centuries, however, nursing duties fell mostly to relatively ignorant women.

In the 17th cent., St. Vincent de Paul began to encourage women to undertake some form of training for their work, but there was no real hospital training school for nurses until one was established in Kaiserwerth, Germany, in 1846. There, Florence Nightingale received the training that later enabled her to establish, at St. Thomas's Hospital in London, the first school designed primarily to train nurses rather than to provide nursing service for the hospital. Similar schools were established in 1873 in New York City, New Haven (Conn.), and Boston. Nursing subsequently became one of the most important professions open to women until the social changes wrought by the revival of the feminist movement that began in the 1960s (see feminism). The late 20th cent. saw growing nursing shortages in U.S. hospitals as stagnant salaries, increasing workloads, and greater job opportunities for women led to falling enrollments in nursing degree programs.