This text provides coherent theoretical and empirical analysis of firms' investment and financing decisions. It assesses the role of uncertainty, financial imperfections, corporate governance and taxation using evidence derived from microeconomic data sets. indeed financially constrained, for fixed investment as well as for R&D projects. The free cash-flow hypothesis holds, that is, managers divert excess funds away for their own interests, but less so in closely controlled companies. In accordance with the real option theory, the results suggest that uncertainty leads firms to adopt a wait...