Florian Witold Znaniecki (15 January 1882 – 23 March 1958) was a Polish philosopher and sociologist. He shifted his focus from philosophy to sociology. He is a major figure in the history of Polish and American sociology, the founder of Polish academic sociology, and of an entire school of thought in sociology. Florian Witold Znaniecki won international renown as co-author, with William I. Thomas, of the study, The Polish Peasant in Europe and America (1918–1920), which is considered the foundation of modern empirical sociology. Florian Witold Znaniecki made major contributions to sociological theory, introducing terms such as humanistic coefficient and culturalism. He was the 44th President of the American Sociological Association (for the year 1954).
Florian Witold Znaniecki founded the Polish Institute of Sociology, the fifth-oldest sociological institute in Europe. The Institute organized Poland's first academic sociologists' conference. Due to his role as founder of so many of its building blocks, Znaniecki is considered as one of the fathers of sociology in Poland. Florian Witold Znaniecki figures among eminent sociologists of the world.
Florian Witold Znaniecki established the first Polish department of sociology at Adam Mickiewicz University where he worked from 1920 to 1939. His career in the US begun at the University of Chicago (1917 to 1919) and continued at Columbia University (1932 to 1934 and 1939 to 1940) and at the University of Illinois at Urbana-Champaign (1942 to 1950). Due to his past political activism, he was unable to secure a post at a major university. From 1912 to 1914 he lectured at a novel women's institution of higher education, the Advanced Pedagogical Courses for Women. Znaniecki became an expert on Polish migration, in 1914 authoring for the government a 500-page report, Wychodźtwo Sezonowe (Seasonal Migration). It was his collaboration with Thomas that marked the transition in Znaniecki's career from philosopher to sociologist. Their work culminated in co-authoring of The Polish Peasant in Europe and America (1918–1920), considered a sociology classic.
Jerzy Szacki wrote that Znaniecki's major contributions include: the founding of sociology in Poland; his work in empirical sociology; and his work in sociological theory. Jerzy Szacki also noted that Znaniecki sought to bridge a number of gaps: between empirical sociology and more theoretical approaches; between objectivity and subjectivity; between humanistic and naturalistic methodologies and viewpoints; and between American and European intellectual traditions.