This paper considered various combinations of financing instrument that makes up the capital of a firm. Various relevant concepts were properly defined and narrated; this includes capital structure’s scope and importance, profitability, solvency and flexibility. Major theories of capital structure were reviewed, such as MM theory, Agency theory, Trade off theory, Signaling theory, Pecking order theory and Free cash flow theory. The determinants of capital structure of some countries across the globe were assessed such countries include, Pakistan, Libya, Turkey, Ghana, Sri Lanka, India, South Africa, Nepal, Egypt, United States, China and United Kingdom. The paper discovered some specific country factors such as cultural setting, development of capital markets, monetary policies, political risk and fiscal policies as major determinants of capital structure. The paper recommends that major country specific factors should be considered carefully in determining the capital structure of a firm.