[1] He worked closely with G. Stanley Hall during his time at Clark University, and his dissertation—published in Pedagogical Seminary, which later became the Journal of Genetic Psychology—focused on "Psychoanalysis of Freud and Adler.
Sumner also developed a relationship with James P. Porter, the dean of Clark University and professor of psychology.
[7]: 217–218 Sumner returned to Lincoln University as a graduate student and as a teacher of religious study, psychology, philosophy, and German.
Sumner kept in contact with Hall, asking for assistance and consideration for a fellowship award to study "race psychology" at Clark University.
His education was postponed in 1918 when he was drafted by the United States Military[7]: 220–221 He was sent to Camp Meade Maryland for basic training with the 48th Company, 154 Depot Brigade.
[7]: 221–223 Sumner's area of focus was in investigating how to refute racism and bias in the theories used to conclude the inferiority of African Americans.
[6] In his time at these universities he faced financial difficulty, because white research agencies refused to provide funding for him.
[13] Sumner is credited, along with Max Meenes and Frederick P. Watts, with helping develop the psychology department at Howard University.
He also is known for teaching social psychologist Kenneth B. Clark, an influential figure in the civil rights movement.
He then moved on to Howard University in fall 1928, and became the acting chairman and professor, until 1930 upon which time he became the fully appointed chair of Psychology and succeeded in making the department independent from Philosophy.
[15][16] In an attempt to show support and praise for the excellence of his students, Sumner created an incentive program.
Upon receiving his application, the SSPP council amended its constitution to block Sumner's path to membership.
[21] Sumner's scientific record was outstanding, but it was through his efforts to build and promote better education for African-Americans that he made the most significant impact.
He advocated for more funding for African-American schools and teachers, and he taught at Howard University for over thirty years.
In 1926, Sumner viewed the African American culture as younger as it was only a few hundred years removed from savagery and less than a century from slavery, while those of Whites was more a pinnacle of Western Civilization.
His goal was to culturally elevate the African Americans and stressed the importance of learning trades such as carpentry and plumbing.
White historians were charged for being biased with "negligence in omitting significant portions of Black history from their writings.
Sumner mentioned that the Negro race cannot be denied that it has produced individuals whose cultural status plainly warrants a higher education.
[citation needed] Sumner died of a heart attack while shoveling snow outside his home in Washington, D.C., on January 11, 1954.
[23] He received a military honor guard in memory for his service during World War I. Sumner was buried at Arlington National Cemetery in Virginia.