‘The Hawthorne Effect’ is a phrase frequently employed in textbooks and other academic discourse. It appears to have been coined over 50 years ago and alludes to the outcome of research undertaken two decades earlier. This paper seeks to elucidate how the term ‘Hawthorne Effect’ has come to be used. A variety of texts will be presented to demonstrate the many different and often contradictory meanings ascribed to the term. A consideration of Guerin's review of research in social facilitation suggests the complexity of issues that seem to be involved in the use of the term ‘Hawthorne Effect’ is such that greater precision is required. Ultimately, we conclude, the term has no useful role in the discussion of research findings. Copyright © 2006 John Wiley & Sons, Ltd.