While a large amount of interest has been shown in the use of peer and self-assessment, few studies have considered the effect of stress on the students involved. None have considered whether the resultant stress itself might account for any noticeable improvements in student performance. The research presented in this paper addresses this question. An experimental design measured the effects of type of assessment and gender on student stress levels and performance. Results suggest that females are more stressed by self-assessment than males and that being subjected to self- and peer assessment, while more stressful, leads to improved student performance in summative tasks.