This chapter explores the origins, characteristics, and modern financial applications of two of the oldest forms of Islamic joint venture contracts: musharaka and mudaraba. A commonly held view of Islamic finance, based on the concept of transaction risk sharing, is that it is ‘equity-based’ rather than ‘debt-based’, and constitutes a ‘quasi-equity’ interest for each investor. This is certainly true for musharaka and mudaraba. They have, however, been adapted for the purpose of corporate and other modern financings to include debt-related elements: this is largely to allow financing institutions to classify these as equity-related or quasi-debt instruments from a risk perspective, whilst retaining the key hallmarks of a joint venture. In some cases, particularly in mudaraba structures, those debt elements closely follow provisions used in syndicated financings. From a Shari’a compliance perspective, then, ‘risk-participation’ remains the essential and distinguishing feature of musharaka and mudaraba, and secures their importance as a vital component of Islamic finance. At the same time, however, Islamic financial institutions will continue to look for ways in which to bridge the ‘risk gap’ between equity and debt instruments.