Collaborative sourcing is defined as a group of organisations combining on the demand side as part of the outsourcing process. Based upon a synthesis of the outsourcing and collaboration literatures, this paper seeks to examine both the benefits of collaborative sourcing and the options available. A series of case studies identifies that a number of alternative collaborative sourcing modes are possible with differing motivations – based on economies of scale but moderated by other influences – intensity – ranging from simply aggregating demand at the contracting stage to establishing a separate entity to actually provide the services – focus – from IT infrastructure through to business processes – and extent – the number of partners involved and activities covered.