# 1. Introduction

Investing in girls’ education has been called “the world’s best investment” (Sperling and Winthrop 2015). Roughly 15 percent of the world’s population in 2016 are girls younger than 18 years old. Educating girls frees them to raise their aspirations and increases their potential to achieve them. It allows them to access better health, higher earnings, and more control over their lives, which subsequently leads to positive impacts on their families, communities, and societies (World Bank 2018b). More and better education for girls and boys contributes to economic growth, labor productivity, and social mobility.

The effects of girls’ education extend across generations. Better educated women tend to have lower fertility rates (Castro Martin 1995). They also have lower child mortality rates: data from 175 countries between 1970 and 2009 show that 51 percent of the reduction in deaths in children younger than 5 years in the past 40 years could be attributed to the increased education attainment in women of reproductive age (Gakidou et al. 2010). In addition, mothers’ education is strongly associated with children’s educational attainment and achievement (Ermisch and Francesconi 2001; Schultz 2002).

Despite all the demonstrated benefits, girls face challenges in education that boys do not. For example, girls’ schooling is more sensitive to both direct costs and opportunity costs than that of boys (King and Winthrop 2015). When girls become teenagers, early marriage and adolescent pregnancy may prevent them pursuing further schooling (Field and Ambrus 2008). Social norms in certain cultural contexts may restrict them from accessing economic opportunities as well, potentially limiting the gains from investing in education. For example, 90 percent of women in Uttar Pradesh, India, reported that they needed their husband’s permission to work (World Bank 2018b). Even when women participate in the labor market, they are less likely to find a job. In the Middle East and North Africa, the female unemployment rate is twice that of their male counterparts (ILO 2017). Educating girls increases their control over their own lives – regardless of whether they participate in the formal labor market – and empowers them to advance gender equality in other areas.

Globally, the gender gap in primary and secondary schooling has significantly narrowed – and in some countries, reversed – over the last two decades (Psaki, McCarthy, and Mensch 2018), but 130 million girls remain out of school (UNESCO 2016 ).<sup>2</sup> However, global averages mask the large variation in gender inequality at the regional and national levels. In many countries, girls are still more likely to be excluded from education (UNESCO 2016 ). Girls also complete less schooling than boys. Gender inequality (favoring boys) in primary completion remains in 60 of all 177 countries with available data (Figure 1A) and is more prominent in poor countries: 21 of the 25 countries with a gap larger than 5 percent are low‐ and lower middle‐income countries. For lower secondary education, access is still much more limited for both boys and girls, with only 50 percent of girls and boys finishing lower secondary education in low and middle‐income

> 2 <mark>The 130 million girls out of school include 32 million out of primary, 29 million out of lower secondary, and 69 million out of upper secondary.</mark>

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