PIP: The relationship between population growth and development has long been a controversial topic in the economic development literature. Early work by Hoover and Coale and more recent work by Blanchet suggest that high fertility suppresses per capita income growth. However, recent work by Kelley and Srinivasan are ambivalent about such a neo-Malthusian relationship between population growth and economic growth. The authors examine these conflicting positions. They emphasize that the rates of both population growth and income growth are endogenous variables within a general equilibrium framework. An endogenous growth model with endogenous fertility is then developed. It is found that when all exogenous variables are controlled for, there exists an inverse relation between population growth and economic growth. However, when some exogenous factors change, such as an improvement in technological progress, the relation becomes ambiguous. This suggests that the conflicting findings in the literature may be because of the presence of substantial heterogeneity in unobserved variables across countries and over time in cross-country panel data sets.