Clarence Ollson Senior was born to Joseph Cressey and Margaret (Ollson) Senior on June 9, 1903, in Clinton, Missouri. He graduated from Missouri Wesleyan Academy in 1923 having interrupted his education for two years to help support his family. He attended Kansas City Junior College and received a B.A. degree in sociology from the University of Kansas in 1927. While at the University of Kansas, Senior was a member of the editorial board of The Dove, a student newspaper printed on pink paper and branded as radical. Senior ultimately completed his formal education by taking a Ph.D. in history from Columbia University in 1955.
During the intervening years, 1927-1955, while extending his expertise as a socialist theoretician and activist, as a labor journalist, and as a specialist in Inter-American affairs, especially in the areas of economics, land reform and labor, Senior managed two partial years of graduate study at the University of Vienna and the International People's School of Elsinore, Denmark.
From 1927 to 1929 he was Field Secretary of the Cleveland Adult Education Association and Secretary of the Cleveland Labor College. He had gained additional experience during his college years as Chairman of the Midwest Student Conference of the League for Industrial Democracy. In 1929 he became national executive secretary of the Socialist Party of the United States, serving as Norman Thomas' presidential campaign manager during the elections of 1932 and 1936. One of his last official acts as secretary was to organize the 1935 Continental Congress of Workers and Farmers, in order to give an outlet for teamwork among like-minded labor organizations.
During 1937 Senior was labor editor for The Milwaukee Leader, a socialist newspaper. In 1938, serving as executive secretary for the Keep-America-Out-of-War Congress, he was unsuccessful in his attempt to promote labor solidarity across the border by organizing a labor delegation to Mexico. Living in Mexico in 1939-1940, Senior was on the Faculty of the Mexico City Institute for the Study of Latin America, was the head of the City of Mexico Bureau of the Information Center for the Americas, and was associated with the New York Committee on Cultural Relations with Latin America. He assisted the American Friends Service Committee in planning and implementing workcamps and service seminars in Mexico.
His work for the Information Center for the Americas led to a teaching position at the University of Kansas City in September, 1940, where he taught Mexican Civilization and Municipal Government, was the Director of the Inter-American Institute, and pioneered one of the earliest “Semester in Mexico” programs, eliciting support from both the Rockefeller Foundation and other colleges and universities.
In 1942 Senior went to Washington to do governmental research on Mexican land development and other Latin American topics for the United States Board of Economic Warfare, the National Planning Association, and the Foreign Economic Administration. At the same time he was a consultant to the United States-Mexico oil commission. Accepting a teaching and research post as director of the Social Science Research Center at the University of Puerto Rico, Senior specialized in Puerto Rican migration and also acted as a consultant to the Puerto Rican Department of Labor. After three years, he returned to the United States as director of field work for a Columbia University study of Puerto Rican migrants in New York City. At the same time, he was a lecturer in sociology at Columbia, and in 1951 became the chief of the Migration Division of the United States Department of Labor with headquarters in New York City.
After receiving his doctorate in 1955, Senior undertook Central and South American research for himself and several agencies of the government. He has authored an impressive list of books, the most significant of which is Land Reform and Democracy, published in 1958. It contributed to the break-up of the feudal land system in Latin American countries. His Strangers-Then Neighbors: From Pilgrims to Puerto Ricans (1961), discusses Puerto Rican migration in comparison to that of other ethnic and racial groups, and the accompanying problems of prejudice and discrimination.
Presently professor of sociology at Brooklyn College of the City University of New York, Senior is a past member, 1961-1968, of the New York City Board of Education. He was married in 1934 to the former Ruth Louise Miller, and has one son, Paul Norman Senior.
