This habilitation thesis consists of an introduction and nine chapters which comprehensively present my contribution to the research of tax havens and financial secrecy. Eight chapters have been previously published or are forthcoming as articles in the following academic journals: Economic Geography, Social Indicators Research, Development Policy Review (two chapters), Post-Communist Economies (two chapters), Applied Economics Letters, Journal of International Development (all indexed in the Web of Science). The final chapter is currently under consideration for publication in International Tax and Public Finance. The introduction briefly describes the common threads and conclusions of my habilitation thesis and provides a summary of the findings of each of the following chapters.