Eleven organizations experienced in developing pertinent information-sharing relationships and procedures were asked to identify practices that could be adopted by others to promote successful sharing of information on computer-based vulnerabilities and incidents and to overcome related challenges. All of the organizations identified trust as the underlying element essential to successful relationships. Among the challenges, one of the most difficult is overcoming new members' initial reluctance to share information. Other challenges include: (1) developing agreements on the use and protection of shared information; (2) obtaining adequate funding to cover the cost of items such as Web sites while avoiding seeking contributions intended primarily to promote the interests of an individual organization; (3) maintaining a focus on emerging issues of interest to members; and (4) maintaining professional and administrative staff with appropriate skills. Abbreviations, notes, figures, appendixes