Alpha Zeta Omega was founded in Philadelphia, at the Philadelphia College of Pharmacy and Science, which is now called the University of the Sciences in Philadelphia. The leader and originator of this group was Ephraim G. Sless. The original members (also known as fraters) were:
These eleven men secretly started a pharmaceutical fraternity they dubbed the Dead Men's Club. Soon after its founding, Harry Althouse was added, and as its members then numbered twelve, the group was often referred to as "The Dozen". Later, Dr. Lawrence Rosenfeld, an eminent Philadelphia Bacteriologist, also became a member, but the name of "The Dozen" persisted. Because of strenuous opposition to the formation of new organizations at the Philadelphia College of Pharmacy and Science by older fraternities and clubs, the newly formed Dead Men's Club would exist as a secret society for several years.
Alpha Zeta Omega was formed for the purpose of academic support; the original stated goal was to ensure 100% graduation of its members. Members participated in a structured series of quizzes, designed and executed by the members most proficient in the particular subject under discussion. These frequent study sessions resulted in bringing together the social life of the members. In 1921, the Dead Men's Club boasted 100% graduation of its 13 members. In addition to the original goal of "100% graduation" the purpose of the Fraternity is now designated chiefly as "to spread the spirit of Fraternalism, Brotherly Love, Friendship and Good Will towards Mankind."
The original constitution of AZO was drawn up by A.M. Bernstein and D.L. Dyen. Stanley Rosenfeld was elected the first "Supreme Directorum" (President) of the Fraternity. The original 13 members termed themselves the Alpha Chapter. The Supreme Chapter, consisting of Supreme Officer and delegates from subordinate chapters, meet regularly twice a year in January and July. At the 1925 Convention in Newark, NJ the Philadelphia Alumni Chapter was chartered, which nullified the charter of the Alpha Chapter. The "Alpha" fraters therefore became charter members of the Alumni Chapter of Philadelphia.
The fraternity is organized by chapters, each representing a specific pharmacy school or geographic area. Chapters may be formed by undergraduates, alumni, and in some instances are "mixed"—containing both undergraduate and graduate members.
As the fraternity began to grow in its early years, it became necessary to hold a yearly convention. The first such affair took place at the Hotel Walton, Philadelphia in June 1922, with E. Fullerton Cook, Chairman of the Pharmacopoeia Revision Committee, as guest and toastmaster. At times there have been as many as 3 conventions per year. Currently, two meetings are held each year—a National Convention in July and a Regional Convention in January.
In 1939 a Ladies Auxiliaries was established at several chapters for the wives of AZO fraters, and at the Detroit Convention in 1940, a National Auxiliary was founded.
After the "Dead Men's Club" graduated, the group held its first official gathering at the home of Abe M. Bernstein. It was at this time decided to change the name of the organization to "Alpha Zeta Omega Fraternity". As it was the custom at the time to use Greek letters to designate fraternities, AZO was renamed such because:
In 1937, the Ohio River Floods caused considerable damage to pharmacies owned by several members. An emergency session of the fraternity was called and a support drive was held to assist those members' businesses that were damaged or destroyed in the flood. In 1938, plans to offer insurance to the members of the Fraternity were adopted, and when finalized, $100,000 worth of insurance was written.
In June 1946, AZO presented funds for the pharmacy of the Hadassah Memorial Hospital in Palestine. This was part of $15,000 pledged by AZO to build a pharmacy building at the hospital.
In 1956, AZO took on as its cultural program, the task of raising money for the Hebrew University in Israel. The stated goal was to raise $100,000 in 3 years, however, the fraternity surpasses its goal and raised $103,000 in just two years.
In 1961, a book titled "40 Years of AZO" was published, detailing the history of AZO. It was a 360-page, hard-cover printed volume, distributed to fraters and chapters nationwide, as well as pharmacy school libraries nationwide. Additional historical publications would follow, outlining the histor of AZO from 1960 to 1970, and then again from 1970 to 1980.
In the early 1970s, AZO began admitting women as members for the first time, and thus became a co-ed fraternal organization.
In 1976, the founder of AZO, Ephraim G. Sless, died. In honor of their late founder, the membership began a campaign to establish scholarships across the USA and in Israel.
After the events of September 11, 2001, AZO started a project to benefit the Dean Street Heroes Fund, N.Y. Fire Dept., Engine Co. 219.
After the devestation caused by Hurricane Maria to Puerto Rico, where one of AZO's chapters resides, a project was started to benefit the rebuilding of the territory.