This paper explains the causes of gender inequality in education and analyses how it impacts economic growth, development, investment, and population dynamics. The paper treats gender inequality in education as an endogenous variable within the development system, demonstrating that it can be explained to a considerable extent by reference to broader economic, social, and cultural determinants. The analysis examines the macro-level consequences of gender education gaps — in terms of human capital formation, labour force participation, fertility rates, and economic productivity — and makes the case for gender-sensitive education investment as a high-return development strategy, with particular relevance to Pakistan and comparable developing economies.