In recent years, ethical issues have become increasingly important for all psychologists, working in professional fields of application or in adacemic teaching and research. This paper reviews some of the historical factors and issues that have been significant in the development of ethical codes for psychological societies and associations. It describes some of the difficulties associated with the development and policing of a comprehensive ethical code, and discusses the roles of codes of ethical conduct in the evolution of an «ethical environment» within psychology as a profession.