How much do we really know about growth and finance?

During the past twenty-five years, development economists have made a major shift toward a more mainstream, market-oriented approach to the financial sector. Economists now take for granted that a well-developed financial sector contributes to economic growth. But until recently there was surprisingly little solid evidence to support this view. ; This article assesses the econometric evidence about the finance-growth relationship. The author first describes the regression framework that has become the standard for assessing this relationship. He outlines some methodological reservations about the evidence used to establish this consensus, pointing out the drawbacks of using aggregate measures of activity. ; Over the last decade, a large body of empirical work using this framework has provided results that relate different dimensions of financial sector development to economic growth. The observed relationships in these studies appear convincingly to be causal, from finance to growth, and not the result of simultaneity or reverse causality. However, the author points out, the literature has not yet adequately explained what happens when the financial sector deepens or how that deepening affects behavior and economic growth. ; Research so far provides policymakers little guidance about how best to develop the financial sector or about the optimal sequence of developments. But the next generation of research has already begun to delve into the \"black box.\" The author discusses a few of these studies that attempt to show how financial deepening effects are transmitted into the real sector.