Limited information is available regarding the factors that promote persistence by women in engineering programs. Stated simply, the problem is that the number of women engineers continues to fall short in comparison to the gender ratio of women to men in the population in the U.S. (BEST, 2002) and worldwide (Hersh, 2000). More women engineers are needed in general and in proportion to male engineers. This study addressed two questions. (1) What are the factors that support women in engineering? and (2) What are the factors that attract women to and help them to persist in a career in engineering? The methods consisted of a search of related research to identify probably factors followed by qualitative interviews with program persisters and switchers. The most frequently cited factors were selected for inclusion in the interview protocol for the qualitative portion of this study. They were: (a) faculty support, (b) class environment, (c) department environment, (d) attraction to another discipline, (e) parental encouragement, and (f) self-confidence. The result was an evaluation of the relative merits of the factors for persisters and switchers. Additionally a new metaphor relating to force field analysis is proposed. This metaphor was supported by the findings of the study whereby persisters reported fewer restraining forces while switchers reported fewer driving forces. The two driving forces that are common among persisters and switchers are formal support programs and peer support programs. Strengthening these two programs would increase the driving forces for all students. These findings will assist faculty, advisers, and program planners to better meet the needs of women in engineering programs and likely help to reduce the attrition rates of women in engineering. Interview Questions for Persisters are appended. (Contains 3 figures and 2 tables.)