He attended Virginia Union University where he studied anthropology, black studies (didn't exist as a field of study until the 1960s) and economics, graduating in 1922 with a Bachelor of Science degree. Harris went on to earn an M.A. in economics from the University of Pittsburgh in 1924. It was his masters' thesis, The Negro Laborer in Pittsburgh, that started his lifelong examination on the African American labor force.
Continuing with previous writings, Harris wrote his Ph.D thesis on the rift between African American and white labor in the United States. In 1930, he became the second African American to receive a doctorate in Economics in the United States, following Sadie Mosell Alexander. The following year, he collaborated his thesis with political scientist, Sterling Spero, to produce a famous study of African American labor history entitled The Black Worker, the Negro & the Labor Movement. Harris believed that African Americans needed to contribute to the development of a working-class political party in the United States. He expressed dislike for other strategies like rebellion, secession, or the various Back to Africa movements — which Harris described as "Negro Zionism" — led by such figures as Marcus Garvey and Haile Selassie I.
In The Black Worker, Spero and Harris asserted that African Americans could put an end to the racial antagonism in the working class. They wrote about the history of the racial predicament between whites and blacks had stemmed from the days of slavery. They argued that many African Americans had just recently migrated to the urban setting, and had been unaware of trade unionism and its benefits. They stated that the anti-union beliefs held by organizations such as the National Urban League also provided for the racial division seen in the working class between blacks and whites. Harris also was the author of a Progressive Labor Party pamphlet in 1930 that called for the formation of a working-class political party in the United States.
Harris, along with Frazier and Bunche, led the attack on the older generations at the NAACP's 1933 Amenia Conference. Harris' radical beliefs prompted a 1935 report entitled the Harris Report suggesting that the NAACP take a more active and affirmative stance on race relations in the United States. As the Great Depression progressed, Harris' radicalism declined. As Harris wrote in the 1957 introduction to his personal collection of essays, he was "emerging from a state of social rebellion [while] still adher[ing] somewhat to socialistic ideas by the late 1920s." He published his most famous economics work in 1936, The Negro as Capitalist: A Study of Banking and Business. In the work, Harris wrote about the growing anti-business sentiment of the Great Depression. Harris argued that black businessmen were under the false sense of racial solidarity between whites and blacks. He said that African Americans needed to participate in trade unionism with white businessmen. This was the reason for the problems in the development of black business. Harris concluded that the black middle class was using their racial pride and unity to support businesses controlled by the American middle class. He felt that blacks were not reaching out to whites, and black business would not grow if there was no interracial trade. In reference to black complaints against Jewish businessmen, Harris said:
In their confusion, the masses are led to direct their animus against the Jew and against whiteness. The real forces behind their discomfort are masked by race which prevents them from seeing that what the Negro businessman wants most of all is freedom to monopolize and exploit he market they provide. They cannot see that they have no greater exploiter than the black capitalist who lives upon low-waged if not sweated labor, although he and his family may and often do, live in conspicuous luxury.Despite the heavy criticism against fellow black businesspeople, Harris' book achieved notability and recognition in the field of economics during the Great Depression. In 1937, Harris founded the liberal Social Science Division of Howard University, and served as the group's leader through the late 1930s and early 1940s.
Harris left Howard in 1945 and moved to the University of Chicago, and became one of the first African American academics with a high position at a historically white institution. His move was facilitated on part of the efforts of Chicago economist Frank Knight, one of the founders of the famed Chicago School of economics that fostered the likes of Noble Prize-winning economists Milton Friedman and George Stigler. Knight had been publishing many of Harris' papers on the thematics of economic doctrine in the Journal of Political Economy since the late 1920s when Harris was at Howard. With his move to Chicago, Harris' economic ideologies also seemed to change. His writings took more of the tone of orthodox economics, and his previous defense of Karl Marx and other radical economists had turned into critical examinations of the works of these men.
Harris expressed deep concerns about the Soviet Union's totalitarian direction led by Joseph Stalin in works such as Black Communist in Dixie, published in the National Urban League magazine, Opportunity. However, Harris became silenced on the topic of race, and did not write about it for the remainder of his academic career. Harris spent the rest of his life at the University of Chicago and died on November 18, 1963.