Until recently, digital libraries have provided free access to either limited resources owned by an organization or information available in the public domain. For digital libraries to provide access to copyrighted material, an access control and charging mechanism needs to be put in place. Electronic commerce provides digital libraries with the mechanism to provide access to copyrighted material in a way that will protect the interest of both the copyright owner and the digital library. In fact, many organizations, such as the Association for Computing Machinery (ACM) and the Institute of Electrical and Electronics Engineers (IEEE), have already started to make their collections available online. The subscription model seems to be the favourable option at this point of time. However, for many ad hoc users, the subscription model can be expensive and not an option. In order to cater to a wider range of users, digital libraries need to go beyond the subscription models and explore other possibilities, such as the use of micro payments, that appear to be an alternative logical solution. But, even before that can happen, digital libraries will need to foremost address a number of outstanding issues, among which including access control, content management, information organization, and so on. This chapter discusses these issues and challenges confronting digital libraries in their adoption of e-commerce, including e-commerce charging models.