Having skill does not necessarily mean more self-confidence in that skill, as shown in four panels, from 2003 to 2015 (n ≈ 983,934), of self-assessments by eighth graders in the Trends in International Math and Science Study (TIMSS). Within a given country, self-judgments of math and science skill correlated positively with actual performance, but at the level of country average the correlation flipped. Students in countries with the best average performance held the most negative self-views of their skill, whereas students from nations with lowest average performance tended to hold the most favorable self-views. National differences in long-term orientation (LTO) versus short-term orientation (STO) accounted for this performance/perception paradox. Although LTO was associated with superior TIMSS performance, it also was associated with a general humility about the self. STO was related to lower objective performance but self-aggrandizing opinions of skill. Surprisingly, greater self-accuracy was related to individualism.