Publisher Summary This chapter describes the framework of the models of economic growth with endogenous population. The chapter discusses the microeconomics of endogenous population: fertility, mortality, and investment in children. In the chapter,the aim of developing growth models with endogenous population is principally to explain why, as income grows, both birth and death rates fall, and stocks of both human and physical capital per capita increase over time.Review of existing neoclassical growth models with endogenous, but unspecified, population growth, suggests a wide variety of possibilities: multiple equilibria, some of which may be stable and others unstable, characterized by large populations with low per capita incomes or by small populations with high per capita income. Without knowing the ways in which population change is related to the stocks of capital, the level of population and other state variables of the economy, however, there is little to distinguish, which path may be followed.