The Polish Peasant in Europe and America, co-authored by William I. Thomas and Florian W. Znaniecki, is an extensive study of the transformations occurring in Polish society in the home country and among its emigrants in the United States. The five volumes that make up this classic study were published at different times between 1918 and 1920. The main aim of the two authors was of analysing the ways in which – under the impulse of industrialisation processes in Poland and emigration to the United States – peasants were increasingly becoming economically rational workers and drifting away from traditional modes of social organisation and behaviour.