In 1903 and 1905, the entire production of saccharin was sent to a new company in Georgia called Coca-Cola. In the early 1900s, vanilla and caffeine were also produced. In 1917, the company started producing aspirin.

During WWI, Monsanto could no longer import its raw materials from Europe, so it started making its own, which was a major turning point for the company.

In 1919, Gaston DuBois became president and Queeny was named CEO and chairman. In 1928, Queeny´s son, Edgar, became president. The company was listed on the New York Stock Exchange as Monsanto Chemical Works just 17 days before the crash of 1929. Nevertheless, it survived.

In the 1930, Monsanto acquired a number of other companies, including Rubber Service Laboratories, Nitro, the Merrimac Chemical Company, Swann Chemical Company, and the Thomas and Hochwalt Laboratories. In the 1930s, Monsanto entered the plastics business with the acquisition of the Fiberloid Company of Springfield, MA. During WWII, Monsanto used the Thomas and Hochwalt Laboratories in Dayton as a means of becoming involved in research on uranium for the Manhattan Project, which led to the first nuclear bomb. Later, Monsanto operated the Mound (OH) Laboratory as a nuclear facility for the federal government until the late 1980s, and the Dayton Laboratory as a research facility for nuclear-based and other government-funded projects.

In 1949, Chemstrand Corporation was formed by Monsanto as a joint venture with AmericanViscose to produce synthetic fibers. Those products made Monsanto the number one seller of acrylic fiber in the world until that part of the business was spun off to Solutia.

Many other joint ventures followed and Monsanto became involved in other areas including fertilizer, synthetic resins, surface coatings, flavors and condiments.

In 1957, Monsanto moved its headquarters from downtown St. Louis to Creve Coeur. In 1960, the agriculture division was created. As American corn and soybean farmers began to accept the idea of pre-emergence herbicides, the company introduced Lasso herbicide. Roundup post-emergent herbicide followed a few years later.

In 1982 Monsanto scientists genetically modified a plant cell for the first time in history. In 1984, Monsanto started up its Chesterfield Life Sciences Research Center to expans its life sciences division.

From 1985 -1993, major strategic restructuring took place at Monsanto, including the sale of several non-strategic businesses. Monsanto focused its efforts on life sciences, agriculture, pharmaceuticals and food, divesting itself of such products and businesses as AstroTurf, polyethylene film, sorbate food preservatives, Fome-Cor foam board, and Fisher Controls International.

In 1997 Monsanto spun off its chemicals business as Solutia Inc. In 2000 Monsanto and Pharmacia/Upjohn merged into a new company called Pharmacia Corporation. The Monsanto name was kept for the agriculture side of the business. In 2002, Monsanto was again spun off into an independent company, just prior to Pharmacia´s acquisition by Pfizer Inc.

During the course of its history there have been 11 company presidents: John Queeny, Gaston DuBois, Edgar Queeny, Charles Belknap, William M. Rand, Charles A. Thomas, Charles H. Sommer, Edward J. Bock, John W. Hanley, Richard Mahoney, and Robert Shapiro. [The St. Louis Portrait, p. 221, http://www.monsanto.com/monsanto/about_us/company_timeline/index6.html]