This paper reports the results of a study which investigated whether there is a common understanding of the terms plagiarism and collusion between students and staff. Participants made judgements on scenarios describing student behaviour in assessments. The results suggest that although plagiarism is well understood, the same can not be said of collusion. Both staff and students feel that collusion is much more acceptable than plagiarism because some learning is taking place. It appears that there is no consensus on the boundary between collaborative behaviour and collusion.