Growth theory is one of the most important branches of macroeconomics. With the emergence of the 'new' growth theory, human capital accumulation and its role on economic growth has been placed at the forefront of the research in macroeconomics. In this book, we have analysed several theoretical aspects related to the human capital accumulation and endogenous economic growth.In chapter 1, we have presented a survey of the existing theoretical literature on the role of human capital accumulation on endogenous economic growth. Since this is a vast literature, we have surveyed only those theoretical works which have been developed adopting the framework of Lucas (1988). In chapter 2, we have extended the Lucas (1988) model in two directions. Chapter 3 sheds light on the relationship between human capital accumulation and environmental quality. In chapters 4, 5 and 6 of the present book, we have developed growth models of a dual economy in which human capital accumulation is viewed as the source of economic growth and in which dualism exists in the mechanism of human capital accumulation of the two types of individuals- the rich and the poor.