This article presents three studies that provide an in-depth examination of STEM-related supports and barriers. These studies constructed an instrument to identify male and female perceptions of the barriers and supports for pursuing coursework and/or careers in mathematics and sciences domains; to pilot test and refine that instrument; and then to explore gender differences in perceptions of supports and barriers at three different educational levels: middle school, high school, and college. Study 1 involved using literature reviews and in-depth interviews at the three educational levels to broadly identify perceived supports and barriers, and to develop a taxonomy of barrier and supports at each level. Based upon the taxonomy, study 2 involved the construction and pilot testing of a barriers and support instrument. Study 3 involved administering the revised instrument to a large sample of participants at each educational level. Results indicate both gender and developmental differences in perceptions of the barriers and supports for pursuing a math or science curriculum. (Contains 6 tables.)