The Metis project is developing workflow technology designed for use in digital libraries by avoiding the assumptions made by traditional workflow systems. In particular, digital libraries have highly distributed sets of stakeholders who nevertheless must work together to perform shared activities. Hence, traditional assumptions that all members of a workflow belong to the same organization, work in the same fashion, or have access to similar computing platforms are invalid. The Metis approach makes use of event-based workflows to support the distributed nature of digital library workflow and employs techniques to make the resulting technology lightweight, flexible, and integrated with the Web. This paper describes the conceptual framework behind the Metis approach as well as a prototype which implements the framework. The prototype represents a "proof-of-concept" of the Metis framework and approach as we show how it can both model and execute a peer review workflow drawn from a "real-world" digital library. After describing related work, the paper concludes with a discussion of future research opportunities in the area of digital library workflow and outlines how Metis is being deployed to a small set of digital libraries for additional evaluation.