Seymour Lubetzky (1898-2003) was a theoretician and practitioner of cataloguing whose work in the field of catalogue theory was of historical importance not only for American librarianship, but also for the world annals of theory of cataloguing. The paper gives a brief biographical overview, while paying particular attention to his work in the field of theory of catalogue in relation to the principles and objectives of the catalogue and to the methodology used to achieve these objectives, as well as to the cataloguing rules, corporate headings complex and his teaching methodology.