The motivational pattern of adolescents with biased and accurate self-efficacy beliefs in language and/or in math was examined in the current study. A sample of 6119 adolescents completed self-report questionnaires measuring self-efficacy beliefs for language and math, their interest in each subject, persistence, achievement goal orientations, and social goals. Data analyses indicated that (a) underestimation of one's performance, even in regard to a single school subject, was associated to costs and no benefits, (b) accurate or realistic self-appraisals were associated to benefits and no costs, and (c) overestimation of one's performance was more likely to be associated with more costs but not necessarily fewer benefits than realistic self-beliefs. Gender differences were also found. (Contains 3 tables.)