As our nation's need for engineering professionals grows, educators and industry leaders are increasingly becoming concerned with how to attract women to this traditionally male career path. Self-efficacy has been shown to be related to positive outcomes in studying and pursuing careers in non-traditional fields. This paper describes the results of two years of engineering self-efficacy data collected from women engineering students at five institutions across the U.S. This study adds to the growing body of self-efficacy literature via its multi-year, multi-institution design and helps to clarify the impact of the engineering curriculum on self-efficacy. Results indicate that while women students show positive progress on some self-efficacy and related subscales, they show a significant decrease on feelings of inclusion from the first to second measurement period and further suggest a relationship between ethnicity and feelings of inclusion. Additionally, correlations show that self-efficacy is related to women students' plans to persist in this predominantly male discipline.