This paper reports on experiences conducting and evaluating MentorNet, a nationwide structured electronic mentoring (ementoring) program that pairs women engineering students, related science students, and math students with industry professionals and provides support to aid the development of year-long ementoring relationships. MentorNet's goal is to increase the representation of women in science, mathematics, engineering, and technology through the provision of mentoring relationships with industry professionals. It works with a consortium of organizations to recruit mentors and proteges, fund, and advertise. The program involves e-mail messages between mentors and proteges and electronic discussion groups for community building. In the 1998-99 program, 693 industry professionals and 963 students were recruited, and 550 pairs were matched (515 of whom completed the year-long program). After matches were finalized, MentorNet sent out regular discussion suggestions to all pairs. Throughout the year, MentorNet maintained a database for tracking interactions. After actively accepting the ementoring match, more proteges than ementors failed to follow through on their commitments by not responding to their mentors. The ementors had more technology problems than the proteges, which tended to disrupt mentoring. Students were more particular about the requirements for a suitable partner than were mentors. (Contains 18 references.) (SM)