Conducting research in a prison setting is ethically challenging. Because history is full of unethical research conducted in prison settings, researchers are often afraid of doing research in this area. It is argued that too much emphasis has been put on the protection of prison inmates as a vulnerable population. Consequently, too little research is being conducted where the focus is on those factors which serve to make the prison population vulnerable. In this paper ethical questions, emerging when conducting a (...) study on literacy and mental health among Norwegian prison inmates, are presented and discussed. Relevant questions relate to topics which include ethical clearance of the research protocol, the consent procedure, clarification of roles and the publication of the results. The ethical questions are discussed in relation to the four principles of ‘respect for the client's rights and dignity’, ‘competence’, ‘responsibility’ and ‘integrity’ set out in the meta-code of ethics, formulated by the European Federation of Professional Psychologists Associations. The wider relationships between ethics in society, research ethics in general, and ethics when conducting research in a prison setting are also considered. (shrink)