In this chapter we will present a theory of the financing of investment in a modern capitalist economy. Our exposition will closely follow the approach developed by Hyman Minsky, arguably the most important contributor to our understanding of this topic. While Minsky began his research in the 1950s and continued to refine his theory until his death in 1996, his ideas are largely absent from undergraduate textbooks. In addition, his approach has been largely ignored by the mainstream of the profession even though the inclusion of some of his ideas in models similar to the New Consensus provides relevant insights (Lavoie, 2008; Weise and Barbera, 2008). This does not mean that his work was unknown, as it was long embraced by Post Keynesian economists and by Wall Street practitioners who recognized the real-world relevance of Minsky’s arguments. Indeed, a few conventional economists — including some Nobel laureates (some of whom were personal friends of Minsky) — were influenced by his ideas. Still, as we prepare this chapter, there is little doubt that interest in his theory is at an all-time peak (e.g. Lahart, 2007; Chancellor, 2007; McCully, 2007). Indeed, the current financial crisis that began with a collapse of the sub-prime mortgage market in the US in 2007 provides a compelling reason to show how his approach provides students with a grounding in the workings of financial capitalism. Even if the spreading global financial crisis is successfully contained this time around, it is likely that analyses will incorporate a substantial dose of Minsky’s ideas for many years to come.