People not only use social comparisons to evaluate their abilities, they also engage in dimensional comparisons, comparing their own achievement in different domains. Processes of dimensional comparison have contrasting effects on subject-specific self-concepts: downward dimensional comparisons result in higher self-concept in the intraindividually better domain, whereas upward dimensional comparisons result in lower self-concept in the intraindividually weaker domain. Two field studies and 1 experimental study were conducted to investigate whether the effects of downward or upward dimensional comparisons are stronger. In Study 1 (N = 319), downward dimensional comparisons proved to be stronger than upward dimensional comparisons. In Study 2 (N = 1349), the same pattern was found with reading test scores as well as grades as achievement indicators. In Study 3 (N = 81), the authors found larger effects for downward than for upward comparisons in both self-perceived competence and satisfaction with test outcomes in an experimental setting. (Contains 1 figure and 6 tables.)