Thomas (1863-1947) was an American sociologist who, with the help of Polish sociologist Florian Znaniecki, developed and influenced the use of empirical methodologies in sociological research and contributed theories to the sociology of migration. He then went on to formulate a fundamental principle of sociology, known as the Thomas theorem, through which he contended that, "If men define situations as real, they are real in their consequences." This microsociological concept served as a theoretical foundation for the field of symbolic interactionism which was developed by his younger peers, primarily at the University of Chicago where Thomas taught sociology and anthropology for 25 years. In 1918 Thomas was arrested and mired in scandal due to his relationship with a US Army officer's wife. Though charges against him were eventually dropped his moral and academic reputation was permanently damaged and he was dismissed from the University of Chicago. He went on to lecture at the New School for Social Research in New York where he made connections with a younger generation of sociologist who would help restore his reputation. Published in 1923, this was his first work under his own name to appear since the scandal and in it he examined female delinquency, mainly in terms of transactional and casual sex, focussing on socialization and how young women are imbued by society to regard sex and how this affects their behaviours and outcomes. The book demonstrates his earliest known application of the Thomas theorem.