Activities of PIM are often embedded in group or organizational contexts. To work effectively within a group, an individual must manage information not only for his or her personal use but also to share with other members of the group. Obviously, one would like to leverage the activities of others around. Being able to obtain telephone numbers, schedule group meetings, determine the availability of one’s peers, and obtain important collaborative information is invaluable. What are the issues, if any, in leveraging the work of others, in order to incorporate their calendar, contacts, and other information into one’s own PIM system? And what would be involved in sharing one’s own data for use by others? This chapter reviews the host of issues involved in the collaborative use of personal information. Topics covered include motivation, adoption patterns, interaction styles, control over personal information, privacy, and trust. The goal is to facilitate sharing personal information by considering these issues; fully considered, they can enable the cooperative adoption and use of tools to support group information management (GIM).