Description: Achievement goal theorists distinguish two types of approach-oriented goals that students might pursue: mastery goals, which focus on learning and developing skill, and performance-approach goals, which focus on outperforming classmates. In classroom field studies, these goals appear to provide distinct benefits: mastery goals generally predict course interest but not actual performance, whereas performance-approach goals generally predict good performance but not interest. These findings are not easily explained by traditional achievement goal theory, which postulates that performance goals should produce outcomes similar to or worse than mastery goals, but never better (Dweck & Leggett, 1986). Two experiments tested the hypothesis that these distinct goal effects trace to goal difficulty perceptions. In both experiments, participants randomly assigned to pursue a performance-approach goal for a word-game activity perceived their goal to be harder and, therefore, felt more performance pressure and enjoyed the activity less than those assigned a mastery goal. However, participants performed the activity better when pursuing this performance-approach goal instead of a standard mastery goal. Additionally, in Study 2, a mastery goal manipulated to appear more difficult than a standard mastery goal produced effects matching the performance-approach goal. Implications for goal theory are discussed.