Is it always a good idea to be a co-author of an article or other research publication? The issue of co-authorship contains a discrepancy between practice and career development norms on one hand and ethical principles of good research practice on the other. With regard to career development, being involved in many publications is important and sometimes the threshold for what is required to be included on a co-author list is problematically low. Conversely, a person who has made a significant contribution is sometimes excluded from the group of authors. Being a co-author also entails that you can be held accountable for the research and publication meeting the requirements of the research community. So, when is it ethically correct to be a co-author? And what are the potential consequences of unjustified co-authorship?