Participation in student chapters of professional organizations can be considered a form of self-help expected to enrich students through extra-curricular activities, social support and networking. For female students, affiliation with the disciplinary professional organizations (e.g., ASME, IEEE, AiChE, etc.) offers the benefits of networking with coed students and faculty on the basis of substantive interests in their major; while affiliation with the Society of Women Engineers (SWE) offers the benefits of interdisciplinary networking with other female students and faculty in a "safe" environment. The current paper focuses on the differences between female undergraduate engineering students who choose one or the other type of affiliation - or no affiliation, and the effect of affiliation on engineering outcomes such as engineering self-confidence, satisfaction with the major, involvement in extra-curricular activities, and commitment to the major and the profession. Data are taken from an NSF-funded survey of engineering students at Rowan University during the 2000-1 and 2000-2 academic years.