This study examines to what degree opportunities for scientific literacy were provided or denied to college bound and non-college bound students and the extent to which students utilized the available opportunities. An ethnographic approach was employed in this 3-year study of six high schools. Population descriptions and data are presented for four California schools and two schools in Utah. The schools' science curriculum structure, how opportunities are established, and how they are exercised are examined, as are students' science experiences and the schools' emphasis on the attainment of scientific literacy. Included among the study's findings are indications that: (1) teachers give priority to facts, methods, and attitudes; (2) scientific literacy components did not form an integral part of the curriculum; and (3) the size and make-up of the school population influence course offerings, teaching load, and science requirements. It was suggested that consideration should be given to ways of increasing the range of student choices of science courses and of improving the quality of science instruction for all students. (ML)