The relationship between high school sophomores' (N=214) self concepts in science and their science achievement, mental ability, and sex were investigated. The Self Concept in Science Scale was used as a measure of students' self concepts. Science achievement was measured by the students' tenth-grade final examination in biology. The measure of mental ability use was the Otis-Lennon Mental Ability Test (Advanced Form J). Demographic data were obtained from guidance folders and a student questionnaire. Results indicated that a relationship does not exist between students' self concept in science and a measure of science and mental ability and grades. The major conclusion drawn from the results of the study is that students who are high achievers in biology and who have high mental ability will have the highest self concept in science. This conclusion supports the theoretical construct that the perceptual field as perceived by the individual has a specific determining effect on behavior, as well as what may be assimilated into the self. (DS)