This study compares PISA 2003 Mathematics and Science results with TIMSS 2003 Grade 8 Mathematics and Science results, using country mean scores for 22 participants of both studies. In Mathematics, it is found that Western countries generally performed better in PISA than in TIMSS, and Eastern European and Asian countries generally performed better in TIMSS than in PISA. Furthermore, two factors, content balance and years of schooling can account for 94% of the variation between the differential performance of countries in PISA and TIMSS. Consequently, the rankings of countries in the two studies can be reconciled to a reasonable degree of accuracy. In Science, the correlation between PISA and TIMSS country mean scores is 0.95, much higher than for Mathematics. That is, TIMSS country mean scores an explain 90% of the variation in PISA country mean scores.