This paper examines the legal structure of securities lending in Australia, and also Europe, the United Kingdom and United States. It provides an analysis of the widely used industry documents, the Australian Master Securities Lending Agreement and the Global Master Securities Lending Agreement (GMSLA). It outlines the regulation of securities lending and short selling, including restrictions on short selling and the applicable disclosure requirements. It discusses the collapse of Opes Prime and the key Federal Court decision which considered the legal effect of the AMSLA. It also outlines the regulatory responses to securities lending and short selling taken by IOSCO, in Europe, the United States and the United Kingdom during the global financial crisis.