This is the peer reviewed version of the following article: Kamarova, S. and Chatzisarantis, N. and Hagger, M. and Lintunen, T. and Hassandra, M. and Papaioannou, A. 2017. Effects of achievement goals on perceptions of competence in conditions of unfavourable social comparisons: The mastery goal advantage effect. British Journal of Educational Psychology. 87 (4): pp. 630-646, which has been published in final form at 10.1111/bjep.12168 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving at http://olabout.wiley.com/WileyCDA/Section/id-828039.html