In 1921 he was reappointed Assistant at the London School of Economics, and full Lecturer in 1923. A year later he was appointed to the Readership in Sociology, being supported by recommendations from Bronisław Malinowski and C.G. Seligman as well as Dawes Hicks from University College London. He published "The Psychology of Society" in 1921 and by 1964 it had reached its ninth edition and had been translated into many languages ranging from Spanish to Japanese. In 1930 he succeeded Hobhouse to the Martin White Professorship of Sociology at the London School of Economics.