Predictor variables were sought relating to the decision of secondary school students to enroll or not enroll in chemistry and physics courses. Questionnaires were developed and administered to 404 students enrolled in chemistry and 358 not enrolled, and to 472 students enrolled in physics and 475 not taking physics. Rural, suburban and urban schools participated. The factors having the greatest influence on the decision to take chemistry were importance of chemistry to college plans (62 percent), importance to career goals (52 percent), planned college science or science-related major (47 percent), and college requirement needs (42 percent). Factors influencing students not to enroll were greater interest in other subjects (54 percent), fear of failure (36 percent), and belief in non importance of chemistry to career goals (34 percent). College plans, college science or science-related majors, enjoyment of science courses, and importance of physics to career goals were the factors related to taking physics in high school. Lack of interest, fear related to difficulty of physics and fear of failure were cited as reasons for not taking physics. The importance of factors considered was not significantly influenced by the sex of the student, the type of community, or the chemistry or physics curriculum. (Author/EB)