This paper reports findings from a comprehensive evaluation of the first national electronic mentoring program that matches female engineering students with mentors working in industry. The program being evaluated--MentorNet--uses a combination of on-line tools, computer databases, mentoring specialists, and campus and industrial contacts to recruit, match, train, coach, and monitor bimonthly e-mail exchanges between women studying science and engineering fields and mentors working in engineering fields. The paper examines the effects of student-mentor matching algorithms, coaching, engineering field, and mentor and student attributes on a variety of outcome measures, including participant reports, the frequency and substance of communication, and students' interest in persisting in science and engineering. (CCM)