This study investigated how candidates claimed to have made an original contribution to knowledge in the conclusion chapters of 100 PhD theses. Documentary analysis was used to discover how this was explained within theses at selected universities in three countries. No other documents were accessed and neither were candidates, supervisors or examiners contacted. The evidence showed that the function of Discussion and Conclusion chapters was interpreted differently between disciplines and national academic traditions. The relative size of conclusion chapters to other chapters was consistently small. Explicit claims for originality and contributing to knowledge appeared in 54 per cent of theses thus meeting their universities' stated criteria for PhD awards but were not adequately explained in 46 per cent of theses.