Dr. Nathaniel Chapman was born in Fairfax County, Virginia, to George and Amelia Chapman, on May 28, 1780. He was one of eight children and attended Classic Academy in Virginia. In 1797, Chapman traveled to Philadelphia, Pennsylvania, and began to study medicine. He began to study under the supervision of the famed Dr. Benjamin Rush at the University of Pennsylvania (Penn). Chapman completed his medical degree and graduated with honors in the year 1800.

In 1801, Dr. Chapman traveled to London and Edinburgh, and he studied and toured Europe. During his time in Europe, Chapman authored many political and patriotism articles that were printed in prominent magazines during the time period. After spending time in Europe, he later returned to the United States in 1804 to pursue the medical profession. In 1808, Chapman married Rebecca Biddle.

After his wedding, Chapman established a successful medical practice in Philadelphia and began teaching independently on the subject of midwifery. Midwifery is the practice generally used to help women have a healthy and natural childbirth experience. During these lectures, Chapman's personality and sense of humor, coupled with his ability to relate with patients and his devoted care to the American public, made him a popular practicing physician in the Philadelphia region. Samuel Gross, a colleague, recalled, "Chapman was the prince of good fellows, popular alike with the profession and the people of Philadelphia."

Continuing to write and lecture, Chapman published "Select Speeches, Forensic and Parliamentary." In 1804, he gave a lecture on obstetrics and, as a result of his expertise and detailed knowledge of the subject, was given the privilege to work as a Professor of Midwifery at the University of Pennsylvania at the early age of 26.

In 1812, Chapman was offered the position of chair of Materia Medica. Materia Medica, an organization that collected knowledge about the therapeutic properties of any substance used for healing treatment. In the year 1816, Chapman filled the position as the Chair of Theory and Practice of Medicine until his resignation in 1850. Professor Chapman delivered lectures for nearly 40 years to large classes at the University of Pennsylvania. In addition to lecturing at Penn, Chapman also was invited to lecture at the Hospital at the Philadelphia Alms House and the Medical Institute of Philadelphia.

Chapman published Discoveries on the Elements of Therapeutics in 1817. In 1820, Chapman became involved in the publication of the Philadelphia Journal of the Medical and Physical Sciences. However, Chapman and a number of medical professionals agreed to broaden the Philadelphia Journal of the Medical and Physical Science and, as a result, The American Journal of the Medical Sciences was created and published its first edition in 1828. The journal was to be a resource of articles on medical topics for medical professionals

Chapman remained popular with his colleagues and students; however, he refused to open his mind to new ideas in medicine during a time period when progress in the knowledge of the human body was being made. Even though he was no longer at the head of medical science, Chapman continued to remain an influential medical professional by educating his students and maintaining memberships in many medical associations.

Chapman retired in 1850 due to illness. He died on July 1, 1852, in his Philadelphia home and was buried on July 4, 1852. At the annual meeting of the American Medical Association in 1854, Vice-President Usher Parson noted the death of Dr. Chapman: "Gentlemen we are reminded by the history of the past year of the frailty of human life. Death has removed many of our brethren of this Association. Among others, its first President, Professor Chapman of Philadelphia, a veteran teacher in our oldest medical college." Nathaniel Chapman was a devoted leader and lecturer of his time. His research and his established medical works are still prominent in today's medical field.