His egalitarian vision of education required a diversified student body, and he promoted the adoption of the Scholastic Aptitude Test (SAT) and co-educational classes.

In his later years at Harvard, Conant taught undergraduate courses on the history and philosophy of science, and wrote books explaining the scientific method to laymen.

[8] In 1915, Conant entered into a business partnership with two other Harvard chemistry graduates, Stanley Pennock and Chauncey Loomis, to form the LPC Laboratories.

They opened a plant in a one-story building in Queens, New York City, where they manufactured chemicals used by the pharmaceutical industry like benzoic acid that were selling at high prices on account of the interruption of imports from Germany due to World War I.

The president of Harvard, Abbott Lawrence Lowell, made a counter offer: immediate promotion to professor, effective September 1, 1927, with a salary of $7,000 (roughly equivalent to US$122,782 as of 2025[16]) and a grant of $9,000 per annum for research.

Based on his exploration of reaction rates in chemical equilibria, Conant was one of the first to recognise that the kinetics of these systems is sometimes straightforward and simple, yet quite complex in other cases.

Later work with George Wheland[31] and extended by William Kirk McEwen[32] looked at the properties of hydrocarbons as very weak acids, including acetophenone, phenylacetylene, fluorene and diphenylmethane.

[18] Conant ran a series of experiments with electrochemical oxidation and reduction, following in the footsteps of the famous German chemist and Nobel laureate Fritz Haber.

[53] Alfred North Whitehead, Harvard's eminent professor of philosophy disagreed with the decision, declaring, "The Corporation should not have elected a chemist to the Presidency."

At his inauguration, he accepted the charter and seal presented to John Leverett the Younger in 1707, but dropped a number of other customs, including the singing of Gloria Patri and the Latin Oration.

[62] Conant added new graduate degrees in education, history of science and public policy,[65] and he introduced the Nieman Fellowship for journalists to study at Harvard,[66] the first of which was awarded in 1939.

[68] Conant asked two of his assistant deans, Henry Chauncey and William Bender, to determine whether the Scholastic Aptitude Test (SAT) was a good measure of academic potential.

[72][73] Conant's cool response to the plight of the Jewish academic refugees from Hitler suggest that he shared the anti-semitism common to his social group and time.

[102] In 1935, he attempted to break down the specialization of academic by creating non-departmental university professorships for scholars whose research crossed the boundaries of multiple disciplines.

[105] Although he had no daughters and little interest in the education of women, the exigencies of World War II meant reduced numbers of male students, and this propelled Conant in that direction.

[107] In June 1940, with World War II already raging in Europe, Vannevar Bush, the director of the Carnegie Institution of Washington, recruited Conant to the National Defense Research Committee (NDRC),[108] although he remained president of Harvard.

[115] In February 1941, Roosevelt sent Conant to Britain as head of a mission that also included Frederick L. Hovde from Purdue University and Carroll L. Wilson from MIT, to evaluate the research being carried out there and the prospects for cooperation.

Conant had lunch with Prime Minister Winston Churchill and Frederick Lindemann, his leading scientific adviser, and an audience with King George VI at Buckingham Palace.

[119][120] Conant subsequently moved to restrict cooperation with Britain on nuclear energy, particularly its post-war aspects, and became involved in heated negotiations with Wallace Akers, the representative of Tube Alloys, the British atomic project.

[127] Technical problems dogged the program through 1943, but by late 1944 plants were in operation with an annual capacity of over a million tons, most of which was Buna-S.[132] In May 1945, Conant became part of the Interim Committee that was formed to advise the new president, Harry S. Truman on nuclear weapons.

[135] After the war, Conant became concerned about growing criticism in the United States of the bombing of Hiroshima and Nagasaki by figures like Norman Cousins and Reinhold Niebuhr.

He played an important behind-the-scenes role in shaping public opinion by instigating and then editing an influential February 1947 Harper's article entitled "The Decision to Use the Atomic Bomb".

It was widely expected that Conant would chair the GAC, but the position went to Robert Oppenheimer, the wartime director of the Los Alamos National Laboratory that had designed and developed the first atomic bombs.

[149] The GAC was enormously influential throughout the late 1940s, but the opposition of Oppenheimer and Conant to the development of the hydrogen bomb, only to be overridden by Truman in 1950, diminished its stature.

[156] Conant contributed four chapters to the 1957 Harvard Case Histories in Experimental Science, including an account of the overthrow of the phlogiston theory.

However, after Dwight Eisenhower was elected president in 1952, Conant was again offered the job by the new Secretary of State, John Foster Dulles, and this time he accepted.

West Germany, made up of the zones occupied by the three western powers, had been granted control of its own affairs, except for defense and foreign policy, in 1949.

Konrad Adenauer's deft handling of the issue enabled him to handily win re-election as Chancellor of West Germany in September, but this also strengthened his hand in negotiations with Conant.

[162] At noon on May 6, 1955, Conant, along with the high commissioners from Britain and France, signed the documents ending Allied control of West Germany, admitting it to NATO, and allowing it to rearm.

[170][171] In it, Conant called for a number of reforms, including the consolidation of high schools into larger bodies that could offer a broader range of curriculum choices.