Just a few decades ago in most nations in the world, women completed far less schooling than men. Today, throughout much of the world, the reverse is true, and on average, women complete more years of schooling than men. This essay identifies important cross-national trends in gender inequalities in educational attainment, outlines foundational and cutting-edge research on the topic and suggests directions for future research. We examine US-based explanations for the female-favorable gender gap in educational attainment, and argue that the gender gap must be studied from a comparative and international perspective. While little is known about why women outpace men in education throughout the world, we recommend three potential avenues for future research: (i) the sources of girls' better average academic performance in school, (ii) boys' apparent greater vulnerability to resource deficits within families, and (iii) changing incentives for women and men to complete higher education. We conclude by discussing the potential consequences of the female advantage in educational attainment and the challenges of conducting cross-national educational research.