We present the first evidence that international emigrant selection on education and earnings materializes through occupational skills. Combining novel data from a representative Mexican task survey with rich individual-level worker data, we find that Mexican migrants to the United States have higher manual skills and lower cognitive skills than non-migrants. Conditional on occupational skills, education and earnings no longer predict migration decisions. Differential labor-market returns to occupational skills explain the observed selection pattern and significantly outperform previously used returns-to-skills measures in predicting migration. Results are persistent over time and hold within narrowly defined regional, sectoral, and occupational labor markets.