e-Research is intended to facilitate collaboration through distributed access to content, tools, and services. Lessons about collaboration are extracted from the findings of two large, long-term digital library research projects. Both the Alexandria Digital Earth Prototype Project (ADEPT) and the Center for Embedded Networked Sensing (CENS) project on data management leverage scientific research data for use in teaching. Two forms of collaboration were studied: (1) direct, in which faculty work together on research projects; and (2) indirect or serial, in which faculty use or contribute content to a common pool, such as teaching resources, concepts and relationships, or research data. Five aspects of collaboration in e-Research are discussed: (1) disciplinary factors, (2) incentives to adopt e-Learning and eResearch technologies, (3) user roles, (4) information sharing, and (5) technical requirements. Collaboration varied by research domain in both projects, and appears partly to be a function of the degree of instrumentation in data collection. Faculty members were more interested in tools to manage their own research data than in tools to facilitate teaching. They also were more reflective about their research than teaching activities. The availability of more content, tools, and services to incorporate primary data in teaching was only a minimal incentive to use these resources. Large investments in a knowledge base of scientific concepts and relationships for teaching did not result in re-use by other faculty during the course of the project. Metadata requirements for research and for teaching vary greatly, which further complicates the transfer of resources across applications. Personal digital libraries offer a middle ground between private control and public release of content, which is a promising direction for the design of digital libraries that will facilitate collaboration in e-Research.