In several of his works, he developed the theory of social constructionism, which argues that all knowledge, including the most basic common sense knowledge of everyday reality, is derived from and maintained by social interactions. Together with Peter L. Berger, he wrote the book "The Social Construction of Reality" in 1966. The book was an important part of the move in sociology, and particularly the sociology of religion, away from the view of religion and religious values as central to the social order, arguing that social order is socially constructed by individuals and/or groups of individuals. Since publication, the book has been translated into thirteen different languages and serves as a cornerstone in sociological literature.