The present thesis fills several research gaps in the area of population and economic change with a special focus on developing countries. Departing from the necessity to predict fertility developments in order to estimate population development trajectories correctly it adds with economic explanations to an area otherwise dominated by demographic and anthropologic literature. While in chapter two the interrelationship between globalization and fertility developments is analyzed, chapter 3 focusses - much in line with other non-economic literature- on broader modernization theories for fertility development. After making the case for modernization to be a dynamic driver of fertility decline in these two chapters it presents an analysis of modernization drivers in developing countries in chapter four.Methodologically the present thesis builds upon an empirical strategy involving the estimation of econometric models. It draws upon divers data sets which are (mostly) publicly available and sets together cross-country time-series data. To encounter data specific characteristics it rests on a range of estimators which are capable to derive valid conclusions. Among the major findings are a fertility decreasing role of human capital intensive trade, the necessity of broad and ongoing modernization to curb birth rates and beneficial aspects of exports and institutions for modernizing economically. ; eng