Thesis: The present thesis studies the consequences of the financial expansion initiated at the end of The Glorious Thirty to spur a declining economic growth. Incidentally, this work questions the issue of measuring economic regularities through econometric tools. Thus, the first chapter carries out an in-depth analysis of the methodology that guides a substantial part of the empirical literature on the finance-growth nexus. It highlights an array of statistical issues casting serious doubts on the reliability of previous results, including, in particular, the conclusion that the relationship between financial expansion and economic growth is non-linear. However, our estimates document an overall negative effect of expanding credit to the private sector on growth. This effect, which has intensified over time, appears to be more pronounced in advanced economies. The joint analysis of private and public debt, conducted in the second chapter, shows that public debt tends to be a drag on growth, not initially, but in the aftermath of a crisis if policy makers are unable to pursue a counter-cyclical fiscal policy. It is not the level of public debt but rather its trajectory that affects economic growth. Finally, the last chapter investigates the bailout of municipalities exposed to toxic structured loans. It illustrates a failure in the financial liberalization initiated in France in the 1980s to stimulate local governments’ financing. This work highlights the ambivalence of the support funds.