Henry Joel Cadbury was born on December 1, 1883, to a faith-driven Quaker family in Philadelphia, Pennsylvania. His parents were Joel Cadbury Jr., a relative of the chocolate-manufacturing Cadbury family, and Anna Kaighn Lowry. Joel Cadbury Jr. demonstrated his strong Quaker beliefs when he refused to serve when drafted to the Civil War; instead, he paid a $300 bounty to hire another man to fight in his place and spent his time helping freed slaves begin their new lives in Pennsylvania. As a result of his parents' conviction to their Quaker beliefs, Henry Cadbury was enrolled in Quaker school, graduating in 1899 from William Penn Charter School, the oldest Quaker school in the world.

Cadbury chose to continue his education by enrolling in Haverford College, a Quaker-based school set on the outskirts of Philadelphia. During his time at Haverford, Cadbury worked for the college newspaper, the Haverfordian, eventually working his way up to Editor-in-Chief during his senior year. An interest in the outdoors led him to join the Campus Club, a club dedicated to the planting and maintenance of Haverford's grounds. He became secretary of the Classics Club, treasurer of the Tennis Club, and a member of the gymnastics team. He also earned honors in Greek and Philosophy, a prize for Systematic Reading and Mathematics, was elected to Phi Beta Kappa, and became class president and class poet.

After graduation from Haverford, Cadbury decided that he would choose teaching as his profession, and he enrolled in Harvard University to earn his Master's Degree. In 1904, he was awarded an MA in Greek from the University, and from there, he accepted a position to teach Classics and History at the University Latin School in Chicago. Only remaining at this job for a year, Cadbury decided to return to the Philadelphia area and took a job teaching at Westtown School in Chester County, Pennsylvania.

During his time at Westtown, Cadbury began participating in a faculty Bible study hour, increasing his curiosity about the Bible. As a result, he left his position at Westtown in 1908 to return to Harvard and earned a PhD in Ancient Languages with a specialty in Biblical and Patristic Greek. In 1910, while still working on his PhD at Harvard, Cadbury was contacted by Haverford and asked to replace an absent staff member in the teaching of Greek. He continued to work towards his PhD during school recesses and was awarded the degree in 1914. His dissertation, The Style and Literary Method of Luke, compared the language of the anonymous authors of Luke and Acts with the words used by the author of Mark and "Q" (an ancient document thought by some scholars to be a source used by Matthew and Luke when composing their Gospels). The Style and Literary Method of Luke also examined the medical terminology used by Luke in his Gospel in an effort to determine if Luke was a physician. For the remainder of his life after receiving his PhD, Cadbury was known as the foremost living Luke scholar.

In 1914 at a wedding, Cadbury was reunited with a first cousin once removed, Lydia Brown. The two became engaged in December 1915, and they wed on June 17, 1916. Less than a year later, on June 14, 1917, Lydia gave birth to the couple's first child, Elizabeth. The couple went on to have three more children: Christopher Joel, born September 5, 1921; Warder Henry, born January 3, 1925; and Winifred, born June 28, 1926.

While Cadbury's family grew, World War I was beginning in Europe. As a Quaker, Cadbury held strong pacifist beliefs and became concerned with the drafting of conscientious objectors, especially those who objected due to religious beliefs. Cadbury, who was the chairperson of the Friends National Peace Committee, decided it was time that all groups of Friends joined together to discuss the issue of the draft. The meeting took place in April 1917 at the Young Friend's office in Philadelphia and was composed of representatives from three different groups of Friends. At its second meeting, the new group renamed itself the American Friends Service Committee (AFSC), and Cadbury was incorporated as a member. The AFSC set to work quickly, dispatching volunteers to France to assist in reconstruction and to Russia to provide aid to refugees.

In addition to his work with the AFSC during World War I, Cadbury wrote letters to various press sources. On October 12, 1918, Cadbury wrote a letter to the Philadelphia Public on Haverford College stationary decrying the American hatred and ill will toward the Germans. Readers of the newspaper objected to this statement, labeling Cadbury as anti-patriotic and even anti-Christian. Because of the letterhead used, Cadbury's statement was associated by the public with Haverford College and the alumni of Haverford called for Cadbury's resignation. Cadbury was placed on a one-year temporary leave of absence.

Making use of his new open schedule, Cadbury became a volunteer publicist for the AFSC. As the Allied blockade of Germany began to affect civilians, especially children, by causing starvation and disease, Cadbury felt as though he had to help somehow, so he traveled to France and Germany. Alongside other members of the AFSC, Cadbury feed 580,000 malnourished children for six days of every week. Cadbury spoke at a number of conferences in Europe before returning home to his wife and children.

Cadbury decided to resign from Haverford College rather than face possible dismissal and opted to take a position at the Andover Seminary College, located in Cambridge, Massachusetts. From 1919 to 1926 he taught New Testament Studies at this Harvard-associated seminary school. During this time, Cadbury's reputation for public speaking grew, and he was offered invitations to speak at many seminary schools. These speeches were subsequently published in various religious magazines, including Christian Century. He also did a significant amount of research on the history of religion during this time, most notably on George Fox, founder of the Religious Society of Friends. He published a paper in 1924 debating Fox's view on Oliver Cromwell's army titled "A Disputed Paper of George Fox."

In 1925, when legal problems resulted in the closure of the Andover Seminary College, Cadbury was offered positions with several of the top seminary schools in the United States, including the Yale Divinity School. However, he turned them down to return home to the Philadelphia area and to Bryn Mawr College, the sister school of Haverford. By returning to the Philadelphia area, Cadbury was able to serve on the executive board of the American Friends Service Committee, which held its meetings in Philadelphia. In 1928, Cadbury's brother in-law, who had been serving as president of the AFCS, resigned, and Cadbury was elected to take the position as leader.

As president of the committee, Cadbury administered relief to thousands of people worldwide. The committee aided striking textile workers from a plant in Marion, North Carolina, by providing both financial relief and assistance with new employment placements. In the depressed coal-mining regions in Appalachia, Cadbury worked with President Herbert Hoover, who used government money to match the money Cadbury raised through the AFCS, to provide food to malnourished children by raising more than $400,000. Cadbury helped adults of the same region by encouraging local industries and promoting family planning. The young people of the region were brought together to work together on community projects in the summer.

During his time at Bryn Mawr College, Cadbury was also offered another opportunity he could not refuse. He was contacted by the American Standard Bible Committee to produce a Revised Standard Version of the Bible. He worked with eight other biblical scholars on the New Testament, while seven additional scholars translated the Old Testament.

After six years at Bryn Mawr, Cadbury was due for a sabbatical, so his entire family travelled to Birmingham, England, where they lived at Woodbrooke, a Quaker retreat, for two years. Cadbury frequently travelled to the Friends Reference Library at Friends Research House in London where he discovered an outdated manuscript list of George Fox's books titled the Annual Catalogue. Inside were more than 100 unpublished narratives detailing George Fox miraculously curing people. Cadbury decided to align these narratives to the entries of George Fox's own journal.

Cadbury's research was interrupted by news from Harvard: the man who was Hollis Chair of Divinity at the Harvard Divinity School had died and Cadbury was offered his prestigious position. Though Cadbury did not want to leave the tight-knit Quaker community of Philadelphia, he decided the opportunity to be financially stable while performing the research that fascinated him was one he could not pass up. He accepted the position in fall of 1934 and resigned as president of the AFSC due to time constraints.

In June 1935, Cadbury's Quaker beliefs came to the forefront when he, like all other teachers in the state of Massachusetts, was asked to sign an oath of allegiance to the Constitution of the United States and the Constitution of the Commonwealth of Massachusetts. As a Quaker, Cadbury was opposed to oaths. Though Cadbury could simply file an affirmation due to his religious beliefs, he was pressured by his colleagues to sign the oath. The president of Harvard, James Contant, also objected to the oath but had signed simply to keep Harvard in line with the law. When he discovered that Cadbury so vehemently objected to signing the oath, he decided to use Cadbury to test the constitutionality of the oath. Cadbury sent several letters to the Commissioner of Education until one was finally accepted, and Cadbury was allowed to continue teaching by submitting an affirmation of his views on the matter of signing the oath.

After the outbreak of war in Europe in 1939, the AFSC became involved in aiding civilians of war-torn countries. Cadbury served several roles during World War II. He served as an advisor for men who opposed the draft due to religious reason. He also travelled to Europe to negotiate lifting the blockade of Germany in order to provide food to starving children. Shortly after returning from Europe, Cadbury began suffering from spells of dizziness and fainting, and he was diagnosed with an acute anxiety state that had developed from reactive depression. Cadbury was treated with a few sessions of electroshock therapy as well as counseling and exercise.

Both of Cadbury's sons were old enough to be drafted during the war, and both refused on account of their religious beliefs. As a result, they were sent to the government-established Civilian Public Service (CPS) camps, a place for citizens who refused the draft on account of their religious beliefs. Many of the occupants of these CPS camps felt as though their work as firefighters, medical experiment subjects, aides in mental hospitals, and the like was unimportant to the war. Cadbury aided these camps by visiting and speaking at them to boost morale.

Cadbury was reelected as the chairman of the AFSC in October of 1944. The committee had extended itself to matters of race by opposing the quarantine of Japanese-American citizens to internment camps, for example, and also continued its support of poverty-stricken citizens of both the United States and war-torn Europe. The research Cadbury had been devoted to for the past decade was also coming to fruition. In 1946, he gave a series of talks called the "Shaffer lectures," which were published a year later under the title Jesus: What Manner of Man. The Revised Standard Version of the New Testament was also published in 1946. Though Cadbury had seemingly finally finished his research, he joked about his continuous religious dedication, saying, "I am still trying to translate the New Testament."

The hard work of the AFSC was also recognized. In 1947, the AFSC and its British counterpart was awarded the Nobel Peace prize. In the presentation speech, Gunnar Jahn, then chairman of the Nobel Committee, cited the breadth of the work of the AFSC as the reason for the award, saying, "The Quakers have shown us that it is possible to translate into action what lies deep in the hearts of many: compassion for others and the desire to help them - that rich expression of the sympathy between all men, regardless of nationality or race, which, transformed into deeds, must form the basis for lasting peace. For this reason alone the Quakers deserve to receive the Nobel Peace Prize today." As the current chairman and a founding member, Cadbury was elected to travel to Oslo to receive the award. Though he had to borrow a long-tailed evening coat from the AFSC clothing warehouse, Cadbury spoke excellently at the award ceremony, stressing the need to ease the rising tension between the United States and the Soviet Union in his acceptance speech by saying, "All Europe is rightly anxious about the relations between the United States and the Soviet Union. Here is a place where you can help. Norway, your well loved country, and the other nations of Europe must be the bridge of understanding. You must not take sides with either of us, you must help both of us cooperate."

Cadbury had won one of the most prestigious prizes in the world, and his peace efforts did not cease. He noticed the growth of communist fear in the United States following the end of World War II, and he encouraged his fellow Quakers to stop paying taxes that directly aided the United States military. He also continued speaking at peace conferences and was asked nearly every week to talk at a different place. At one such speaking engagement at Whittier College in California, Cadbury was given his first honorary degree, an LLD. He received five more honorary degrees during the rest of his life.

In March of 1954, Cadbury retired from his position of the Hollis Professor of Divinity. He moved to Pendle Hill, a Quaker retreat in Wallingford, Pennsylvania, and lectured there as well as at Drew Seminary, a nearby school in Madison, New Jersey. Eventually, he began teaching one course at Haverford on the history and philosophy of Quakerism. In addition, a year later he returned to Bryn Mawr College and began teaching a course and even served as chairman of the Board of Directors at Bryn Mawr for one year.

The remainder of Cadbury's life was spent teaching, traveling, and supporting the American Friends Service Committee. He finished writing three books in 1972, including Narrative Papers of George Fox, the work he had started when on sabbatical in Woodbrooke almost 30 years earlier. After he turned 90, he grew more frail. On October 9, 1974, Henry Cadbury died of a cerebral hemorrhage at Bryn Mawr Hospital in Bryn Mawr, Pennsylvania, following a fall down the stairs of his home. ?ö