This study used naturalistic inquiry methods to examine reasons why some members of minority groups, despite discouraging odds, persist in the sciences or science related disciplines. Interviews were conducted with 10 African American upperclassmen majoring in natural science or science related disciplines at a predominately white coeducational research university. Subjects were questioned about their experiences within their respective disciplines and about affective factors influencing their persistence. Three generalized observations were developed from analysis of the interviews: (1) the importance of the development of self-reliance and autonomy to persistence; (2) the role uncomfortable environments play in persistence; and (3) the emphasis on the product (career prospects) of science education rather than the process of science education. Students typically expressed attitudes that were resigned, yet persistent. Among factors influencing persistence were a strong support system comprised of family, friends and home community members; parental expectation of success in college and a desire not to disappoint parents; and a focus on the quality of educational opportunities offered by the university and the necessity of taking advantage of them. (Contains 29 references.) (Author/JLS)