In developing countries, rising incomes, increased demand for more skilled labor, and government investments of considerable resources on building and equipping schools and paying teachers have contributed to global convergence in enrollment rates and completed years of schooling. Nevertheless, in many countries substantial education gaps persist between rich and poor, between rural and urban households and between males and females. To address these gaps, some governments have introduced school vouchers or cash transfers programs that are targeted to disadvantaged children. Others have initiated programs to attract or retain students by expanding school access or by setting higher teacher eligibility requirements or increasing the number of textbooks per student. While enrollments have increased, there has not been a commensurate improvement in knowledge and skills of students. Establishing the impact of these policies and programs requires an understanding of the incentives and constraints faced by all parties involved, the school providers, the parents and the children. The chapter reviews the economic literature on the determinants of schooling outcomes and schooling gaps with a focus on static and dynamic household responses to specific policy initiatives, perceived economic returns and other incentives. It discusses measurement and estimation issues involved with empirically testing these models and reviews findings. Governments have increasingly adopted the practice of experimentation and evaluation before taking steps to expand new policies. Often pilot programs are initiated in settings that are atypically appropriate for the program, so that the results overstate the likely impact of expanding the program to other settings. Program expansion can also result in general equilibrium feedback effects that do not apply to isolated pilots. These behavioral models provide a useful context within which to frame the likely outcomes of such expansion.