At the end of the nineteenth century, most fraternities were exclusively Christian or Jewish and barred membership to individuals based on religion.

Delta Sigma Phi recognizes Charles A. Tonsor Jr. (Christian) and Meyer Boskey (Jewish) as its two primary founding fathers.

Many Jewish members and other minorities left Delta Sigma Phi or joined others, including Meyer Boskey, who withdrew active participation in the fraternity for an extended period.

By this time, Delta Sigma Phi had expanded the number of staff, and a national headquarters was created at the Riebold Building at Dayton, Ohio.

During the war, more than three-quarters of the fraternity's membership served the government in some capacity with half of that number in combat duty overseas.

Some chapters never recovered from the disruptions of World War I. Delta Sigma Phi continued to expand during the 1920s, with many local fraternities and other social clubs petitioning for membership.

Two months after the Wall Street Crash of 1929, Delta Sigma Phi's yearly convention was held in Richmond, Virginia.

In a compromise to several southern chapters, the amendments to the constitution were approved at the 1949 convention while language barring the initiation of non-white and non-Christians was inserted into the fraternity ritual.

Since the ritual was a private document and the constitution a public one, this compromise appeased those who resisted the integration of the fraternity while allowing it to expand to new universities.

While most of the national Greek-letter organizations still had rules restricting membership, a few chapters bucked the edicts and initiated Jews and African Americans.

In 1957, the California Legislature threatened to pass Assembly Bill 758, prohibiting state universities and colleges from recognizing any student organization that "restricts its membership based on either race, color, religion or national origin."

Two years later, the regents of the University of California passed a regulation requiring all fraternities and sororities to sign a certificate stating the organization did not have any discriminatory policies.

A compromise again was reached where the current rules were not to be changed but exemptions were granted to chapters in danger of losing their recognition due to fraternity policies.

In 1962, the Pennsylvania State System of Higher Education joined the University of California by requiring the integration of its fraternities and sororities.

When the chapter intended to initiate an African American who was an All-American athlete and an outstanding scholar, the fraternity responded by offering an exemption, likely to avoid bad publicity.

When Civil Rights legislation was enacted, Delta Sigma Phi was once more a universal brotherhood of man, just as the founders intended.

Delta Sigma Phi established a partnership with Phired Up Productions, a fraternity and sorority recruitment consulting company, to coach its New Chapter Development team.

The publications of the fraternity are often named after its symbols: The pledge emblem is a white circle with a green equilateral triangle set inside of it.

Delegates from undergraduate chapters and alumni group elect members to the Grand Council and vote on amendments to the Constitution or general resolutions.

The program also regularly includes a silent auction through the Fraternity Foundation, breakout educational sessions, service activities, and social activities/excursions.

In 2001, the Kappa chapter at Auburn University had its charter revoked after a Halloween party where members were present in blackface, Ku Klux Klan robes, and simulating a lynching.

[11] In 2014, the chapter at San Diego State University was shut down due to a string of hazing and alcohol violations, and misconduct, including waving dildos at protestors during an anti-rape rally on campus.

[12] In 2024, three members of the University of Texas at Austin chapter, including the vice president, were arrested for allegedly attacking a gay man.