This study compares the Programme for International Student Assessment (PISA) 2003 Mathematics results with the Trends in International Mathematics and Science Study (TIMSS) 2003 Grade 8 mathematics results, using country mean scores for 22 participants of both studies. 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 93% 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.