This paper reports the development of an Academic Social Comparison Scale (ASCS) to measure students' tendencies to socially compare themselves with other students in an educational setting. The 27-item ASCS was then measured in relation to academic self-confidence in a sample of University students, using the Individual Learning Profile (ILP) scale. The study found that making downward academic social comparisons was not very commonly reported and did not relate to academic confidence in any domain measured. Confidence in numeracy, speaking, and hard IT were, however, significantly lower in those students who tended to make more upward social comparisons. The results also showed that the less students reported that they socially compared in general, the more confident they were in reading, writing, and time management. All three subscales of the ASCS showed good reliability when tested 6-9 weeks later. The ASCS showed that female students tended to make more upward academic social comparisons and less downward academic comparisons than male students. In domains such as reading and writing people's confidence was higher if they made fewer academic social comparisons (irrespective of direction), and gender was not an important factor. Results also showed that academic confidence was neither higher nor lower in students who reported making more downwards academic comparisons. This study demonstrates the negative impact on confidence of upward social comparisons, and introduces a social comparison questionnaire specifically tailored for measuring people's tendencies to make social comparisons in the academic domain.