The World Development Report (WDR) has become such a fixture that it is easy to forget the circumstances under which it was born and the Bank's motivation for producing such a report at that time. In the first chapter of this essay, the authors provide a brief background on the circumstances of newly independent developing countries and summarize some of the main strands of the emerging field of development economics. This backdrop to the genesis of the WDR accounts for the orientation of the earlier reports. The thinking on development in the 1960s and 1970s also provides a baseline from which to view the evolution that has occurred since. From the coverage in the second chapter, the authors isolate a number of key issues common to several or all of the WDRs, and the author examine these issues individually at greater length in third chapter. The discussion in third chapter, which builds on the material in the WDRs, presents some views about how far development thinking and, relatedly, policy making have advanced relative to 30 years ago. It asks whether promoting growth, building institutions, tackling inequality and poverty, making aid effective, and defining the role of the state have been rendered more tractable policy wise by the knowledge encapsulated in the WDRs. Chapter four looks ahead and points to some of the big challenges that the Bank might explore through future WDRs and the value it can add through the knowledge acquired from its cross-country operations and research.